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Type | Label | Description |
---|---|---|
Statement | ||
Theorem | recld 15201 | The real part of a complex number is real (closure law). (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘𝐴) ∈ ℝ) | ||
Theorem | imcld 15202 | The imaginary part of a complex number is real (closure law). (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℑ‘𝐴) ∈ ℝ) | ||
Theorem | cjcld 15203 | Closure law for complex conjugate. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (∗‘𝐴) ∈ ℂ) | ||
Theorem | replimd 15204 | Construct a complex number from its real and imaginary parts. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → 𝐴 = ((ℜ‘𝐴) + (i · (ℑ‘𝐴)))) | ||
Theorem | remimd 15205 | Value of the conjugate of a complex number. The value is the real part minus i times the imaginary part. Definition 10-3.2 of [Gleason] p. 132. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (∗‘𝐴) = ((ℜ‘𝐴) − (i · (ℑ‘𝐴)))) | ||
Theorem | cjcjd 15206 | The conjugate of the conjugate is the original complex number. Proposition 10-3.4(e) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (∗‘(∗‘𝐴)) = 𝐴) | ||
Theorem | reim0bd 15207 | A number is real iff its imaginary part is 0. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → (ℑ‘𝐴) = 0) ⇒ ⊢ (𝜑 → 𝐴 ∈ ℝ) | ||
Theorem | rerebd 15208 | A real number equals its real part. Proposition 10-3.4(f) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → (ℜ‘𝐴) = 𝐴) ⇒ ⊢ (𝜑 → 𝐴 ∈ ℝ) | ||
Theorem | cjrebd 15209 | A number is real iff it equals its complex conjugate. Proposition 10-3.4(f) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → (∗‘𝐴) = 𝐴) ⇒ ⊢ (𝜑 → 𝐴 ∈ ℝ) | ||
Theorem | cjne0d 15210 | A number is nonzero iff its complex conjugate is nonzero. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐴 ≠ 0) ⇒ ⊢ (𝜑 → (∗‘𝐴) ≠ 0) | ||
Theorem | recjd 15211 | Real part of a complex conjugate. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘(∗‘𝐴)) = (ℜ‘𝐴)) | ||
Theorem | imcjd 15212 | Imaginary part of a complex conjugate. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℑ‘(∗‘𝐴)) = -(ℑ‘𝐴)) | ||
Theorem | cjmulrcld 15213 | A complex number times its conjugate is real. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (𝐴 · (∗‘𝐴)) ∈ ℝ) | ||
Theorem | cjmulvald 15214 | A complex number times its conjugate. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (𝐴 · (∗‘𝐴)) = (((ℜ‘𝐴)↑2) + ((ℑ‘𝐴)↑2))) | ||
Theorem | cjmulge0d 15215 | A complex number times its conjugate is nonnegative. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → 0 ≤ (𝐴 · (∗‘𝐴))) | ||
Theorem | renegd 15216 | Real part of negative. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘-𝐴) = -(ℜ‘𝐴)) | ||
Theorem | imnegd 15217 | Imaginary part of negative. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℑ‘-𝐴) = -(ℑ‘𝐴)) | ||
Theorem | cjnegd 15218 | Complex conjugate of negative. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (∗‘-𝐴) = -(∗‘𝐴)) | ||
Theorem | addcjd 15219 | A number plus its conjugate is twice its real part. Compare Proposition 10-3.4(h) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → (𝐴 + (∗‘𝐴)) = (2 · (ℜ‘𝐴))) | ||
Theorem | cjexpd 15220 | Complex conjugate of positive integer exponentiation. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝑁 ∈ ℕ0) ⇒ ⊢ (𝜑 → (∗‘(𝐴↑𝑁)) = ((∗‘𝐴)↑𝑁)) | ||
Theorem | readdd 15221 | Real part distributes over addition. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘(𝐴 + 𝐵)) = ((ℜ‘𝐴) + (ℜ‘𝐵))) | ||
Theorem | imaddd 15222 | Imaginary part distributes over addition. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℑ‘(𝐴 + 𝐵)) = ((ℑ‘𝐴) + (ℑ‘𝐵))) | ||
Theorem | resubd 15223 | Real part distributes over subtraction. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘(𝐴 − 𝐵)) = ((ℜ‘𝐴) − (ℜ‘𝐵))) | ||
Theorem | imsubd 15224 | Imaginary part distributes over subtraction. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℑ‘(𝐴 − 𝐵)) = ((ℑ‘𝐴) − (ℑ‘𝐵))) | ||
Theorem | remuld 15225 | Real part of a product. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘(𝐴 · 𝐵)) = (((ℜ‘𝐴) · (ℜ‘𝐵)) − ((ℑ‘𝐴) · (ℑ‘𝐵)))) | ||
Theorem | immuld 15226 | Imaginary part of a product. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℑ‘(𝐴 · 𝐵)) = (((ℜ‘𝐴) · (ℑ‘𝐵)) + ((ℑ‘𝐴) · (ℜ‘𝐵)))) | ||
Theorem | cjaddd 15227 | Complex conjugate distributes over addition. Proposition 10-3.4(a) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (∗‘(𝐴 + 𝐵)) = ((∗‘𝐴) + (∗‘𝐵))) | ||
Theorem | cjmuld 15228 | Complex conjugate distributes over multiplication. Proposition 10-3.4(c) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (∗‘(𝐴 · 𝐵)) = ((∗‘𝐴) · (∗‘𝐵))) | ||
Theorem | ipcnd 15229 | Standard inner product on complex numbers. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘(𝐴 · (∗‘𝐵))) = (((ℜ‘𝐴) · (ℜ‘𝐵)) + ((ℑ‘𝐴) · (ℑ‘𝐵)))) | ||
Theorem | cjdivd 15230 | Complex conjugate distributes over division. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) & ⊢ (𝜑 → 𝐵 ≠ 0) ⇒ ⊢ (𝜑 → (∗‘(𝐴 / 𝐵)) = ((∗‘𝐴) / (∗‘𝐵))) | ||
Theorem | rered 15231 | A real number equals its real part. One direction of Proposition 10-3.4(f) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → (ℜ‘𝐴) = 𝐴) | ||
Theorem | reim0d 15232 | The imaginary part of a real number is 0. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → (ℑ‘𝐴) = 0) | ||
Theorem | cjred 15233 | A real number equals its complex conjugate. Proposition 10-3.4(f) of [Gleason] p. 133. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) ⇒ ⊢ (𝜑 → (∗‘𝐴) = 𝐴) | ||
Theorem | remul2d 15234 | Real part of a product. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℜ‘(𝐴 · 𝐵)) = (𝐴 · (ℜ‘𝐵))) | ||
Theorem | immul2d 15235 | Imaginary part of a product. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) ⇒ ⊢ (𝜑 → (ℑ‘(𝐴 · 𝐵)) = (𝐴 · (ℑ‘𝐵))) | ||
Theorem | redivd 15236 | Real part of a division. Related to remul2 15137. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) & ⊢ (𝜑 → 𝐴 ≠ 0) ⇒ ⊢ (𝜑 → (ℜ‘(𝐵 / 𝐴)) = ((ℜ‘𝐵) / 𝐴)) | ||
Theorem | imdivd 15237 | Imaginary part of a division. Related to remul2 15137. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℂ) & ⊢ (𝜑 → 𝐴 ≠ 0) ⇒ ⊢ (𝜑 → (ℑ‘(𝐵 / 𝐴)) = ((ℑ‘𝐵) / 𝐴)) | ||
Theorem | crred 15238 | The real part of a complex number representation. Definition 10-3.1 of [Gleason] p. 132. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) ⇒ ⊢ (𝜑 → (ℜ‘(𝐴 + (i · 𝐵))) = 𝐴) | ||
Theorem | crimd 15239 | The imaginary part of a complex number representation. Definition 10-3.1 of [Gleason] p. 132. (Contributed by Mario Carneiro, 29-May-2016.) |
⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) ⇒ ⊢ (𝜑 → (ℑ‘(𝐴 + (i · 𝐵))) = 𝐵) | ||
Syntax | csqrt 15240 | Extend class notation to include square root of a complex number. |
class √ | ||
Syntax | cabs 15241 | Extend class notation to include a function for the absolute value (modulus) of a complex number. |
class abs | ||
Definition | df-sqrt 15242* |
Define a function whose value is the square root of a complex number.
For example, (√‘25) = 5 (ex-sqrt 30390).
Since (𝑦↑2) = 𝑥 iff (-𝑦↑2) = 𝑥, we ensure uniqueness by restricting the range to numbers with positive real part, or numbers with 0 real part and nonnegative imaginary part. A description can be found under "Principal square root of a complex number" at http://en.wikipedia.org/wiki/Square_root 30390. The square root symbol was introduced in 1525 by Christoff Rudolff. See sqrtcl 15368 for its closure, sqrtval 15244 for its value, sqrtth 15371 and sqsqrti 15382 for its relationship to squares, and sqrt11i 15391 for uniqueness. (Contributed by NM, 27-Jul-1999.) (Revised by Mario Carneiro, 8-Jul-2013.) |
⊢ √ = (𝑥 ∈ ℂ ↦ (℩𝑦 ∈ ℂ ((𝑦↑2) = 𝑥 ∧ 0 ≤ (ℜ‘𝑦) ∧ (i · 𝑦) ∉ ℝ+))) | ||
Definition | df-abs 15243 | Define the function for the absolute value (modulus) of a complex number. See abscli 15402 for its closure and absval 15245 or absval2i 15404 for its value. For example, (abs‘-2) = 2 (ex-abs 30391). (Contributed by NM, 27-Jul-1999.) |
⊢ abs = (𝑥 ∈ ℂ ↦ (√‘(𝑥 · (∗‘𝑥)))) | ||
Theorem | sqrtval 15244* | Value of square root function. (Contributed by Mario Carneiro, 8-Jul-2013.) |
⊢ (𝐴 ∈ ℂ → (√‘𝐴) = (℩𝑥 ∈ ℂ ((𝑥↑2) = 𝐴 ∧ 0 ≤ (ℜ‘𝑥) ∧ (i · 𝑥) ∉ ℝ+))) | ||
Theorem | absval 15245 | The absolute value (modulus) of a complex number. Proposition 10-3.7(a) of [Gleason] p. 133. (Contributed by NM, 27-Jul-1999.) (Revised by Mario Carneiro, 7-Nov-2013.) |
⊢ (𝐴 ∈ ℂ → (abs‘𝐴) = (√‘(𝐴 · (∗‘𝐴)))) | ||
Theorem | rennim 15246 | A real number does not lie on the negative imaginary axis. (Contributed by Mario Carneiro, 8-Jul-2013.) |
⊢ (𝐴 ∈ ℝ → (i · 𝐴) ∉ ℝ+) | ||
Theorem | cnpart 15247 | The specification of restriction to the right half-plane partitions the complex plane without 0 into two disjoint pieces, which are related by a reflection about the origin (under the map 𝑥 ↦ -𝑥). (Contributed by Mario Carneiro, 8-Jul-2013.) |
⊢ ((𝐴 ∈ ℂ ∧ 𝐴 ≠ 0) → ((0 ≤ (ℜ‘𝐴) ∧ (i · 𝐴) ∉ ℝ+) ↔ ¬ (0 ≤ (ℜ‘-𝐴) ∧ (i · -𝐴) ∉ ℝ+))) | ||
Theorem | sqrt0 15248 | The square root of zero is zero. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ (√‘0) = 0 | ||
Theorem | 01sqrexlem1 15249* | Lemma for 01sqrex 15256. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ 𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴} & ⊢ 𝐵 = sup(𝑆, ℝ, < ) ⇒ ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → ∀𝑦 ∈ 𝑆 𝑦 ≤ 1) | ||
Theorem | 01sqrexlem2 15250* | Lemma for 01sqrex 15256. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ 𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴} & ⊢ 𝐵 = sup(𝑆, ℝ, < ) ⇒ ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → 𝐴 ∈ 𝑆) | ||
Theorem | 01sqrexlem3 15251* | Lemma for 01sqrex 15256. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ 𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴} & ⊢ 𝐵 = sup(𝑆, ℝ, < ) ⇒ ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → (𝑆 ⊆ ℝ ∧ 𝑆 ≠ ∅ ∧ ∃𝑧 ∈ ℝ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝑧)) | ||
Theorem | 01sqrexlem4 15252* | Lemma for 01sqrex 15256. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ 𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴} & ⊢ 𝐵 = sup(𝑆, ℝ, < ) ⇒ ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → (𝐵 ∈ ℝ+ ∧ 𝐵 ≤ 1)) | ||
Theorem | 01sqrexlem5 15253* | Lemma for 01sqrex 15256. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ 𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴} & ⊢ 𝐵 = sup(𝑆, ℝ, < ) & ⊢ 𝑇 = {𝑦 ∣ ∃𝑎 ∈ 𝑆 ∃𝑏 ∈ 𝑆 𝑦 = (𝑎 · 𝑏)} ⇒ ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → ((𝑇 ⊆ ℝ ∧ 𝑇 ≠ ∅ ∧ ∃𝑣 ∈ ℝ ∀𝑢 ∈ 𝑇 𝑢 ≤ 𝑣) ∧ (𝐵↑2) = sup(𝑇, ℝ, < ))) | ||
Theorem | 01sqrexlem6 15254* | Lemma for 01sqrex 15256. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ 𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴} & ⊢ 𝐵 = sup(𝑆, ℝ, < ) & ⊢ 𝑇 = {𝑦 ∣ ∃𝑎 ∈ 𝑆 ∃𝑏 ∈ 𝑆 𝑦 = (𝑎 · 𝑏)} ⇒ ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → (𝐵↑2) ≤ 𝐴) | ||
Theorem | 01sqrexlem7 15255* | Lemma for 01sqrex 15256. (Contributed by Mario Carneiro, 10-Jul-2013.) (Proof shortened by AV, 9-Jul-2022.) |
⊢ 𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴} & ⊢ 𝐵 = sup(𝑆, ℝ, < ) & ⊢ 𝑇 = {𝑦 ∣ ∃𝑎 ∈ 𝑆 ∃𝑏 ∈ 𝑆 𝑦 = (𝑎 · 𝑏)} ⇒ ⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → (𝐵↑2) = 𝐴) | ||
Theorem | 01sqrex 15256* | Existence of a square root for reals in the interval (0, 1]. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ+ ∧ 𝐴 ≤ 1) → ∃𝑥 ∈ ℝ+ (𝑥 ≤ 1 ∧ (𝑥↑2) = 𝐴)) | ||
Theorem | resqrex 15257* | Existence of a square root for positive reals. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → ∃𝑥 ∈ ℝ (0 ≤ 𝑥 ∧ (𝑥↑2) = 𝐴)) | ||
Theorem | sqrmo 15258* | Uniqueness for the square root function. (Contributed by Mario Carneiro, 9-Jul-2013.) (Revised by NM, 17-Jun-2017.) |
⊢ (𝐴 ∈ ℂ → ∃*𝑥 ∈ ℂ ((𝑥↑2) = 𝐴 ∧ 0 ≤ (ℜ‘𝑥) ∧ (i · 𝑥) ∉ ℝ+)) | ||
Theorem | resqreu 15259* | Existence and uniqueness for the real square root function. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → ∃!𝑥 ∈ ℂ ((𝑥↑2) = 𝐴 ∧ 0 ≤ (ℜ‘𝑥) ∧ (i · 𝑥) ∉ ℝ+)) | ||
Theorem | resqrtcl 15260 | Closure of the square root function. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘𝐴) ∈ ℝ) | ||
Theorem | resqrtthlem 15261 | Lemma for resqrtth 15262. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (((√‘𝐴)↑2) = 𝐴 ∧ 0 ≤ (ℜ‘(√‘𝐴)) ∧ (i · (√‘𝐴)) ∉ ℝ+)) | ||
Theorem | resqrtth 15262 | Square root theorem over the reals. Theorem I.35 of [Apostol] p. 29. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → ((√‘𝐴)↑2) = 𝐴) | ||
Theorem | remsqsqrt 15263 | Square of square root. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → ((√‘𝐴) · (√‘𝐴)) = 𝐴) | ||
Theorem | sqrtge0 15264 | The square root function is nonnegative for nonnegative input. (Contributed by NM, 26-May-1999.) (Revised by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → 0 ≤ (√‘𝐴)) | ||
Theorem | sqrtgt0 15265 | The square root function is positive for positive input. (Contributed by Mario Carneiro, 10-Jul-2013.) (Revised by Mario Carneiro, 6-Sep-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 < 𝐴) → 0 < (√‘𝐴)) | ||
Theorem | sqrtmul 15266 | Square root distributes over multiplication. (Contributed by NM, 30-Jul-1999.) (Revised by Mario Carneiro, 29-May-2016.) |
⊢ (((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) ∧ (𝐵 ∈ ℝ ∧ 0 ≤ 𝐵)) → (√‘(𝐴 · 𝐵)) = ((√‘𝐴) · (√‘𝐵))) | ||
Theorem | sqrtle 15267 | Square root is monotonic. (Contributed by NM, 17-Mar-2005.) (Proof shortened by Mario Carneiro, 29-May-2016.) |
⊢ (((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) ∧ (𝐵 ∈ ℝ ∧ 0 ≤ 𝐵)) → (𝐴 ≤ 𝐵 ↔ (√‘𝐴) ≤ (√‘𝐵))) | ||
Theorem | sqrtlt 15268 | Square root is strictly monotonic. Closed form of sqrtlti 15396. (Contributed by Scott Fenton, 17-Apr-2014.) (Proof shortened by Mario Carneiro, 29-May-2016.) |
⊢ (((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) ∧ (𝐵 ∈ ℝ ∧ 0 ≤ 𝐵)) → (𝐴 < 𝐵 ↔ (√‘𝐴) < (√‘𝐵))) | ||
Theorem | sqrt11 15269 | The square root function is one-to-one. (Contributed by Scott Fenton, 11-Jun-2013.) |
⊢ (((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) ∧ (𝐵 ∈ ℝ ∧ 0 ≤ 𝐵)) → ((√‘𝐴) = (√‘𝐵) ↔ 𝐴 = 𝐵)) | ||
Theorem | sqrt00 15270 | A square root is zero iff its argument is 0. (Contributed by NM, 27-Jul-1999.) (Proof shortened by Mario Carneiro, 29-May-2016.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → ((√‘𝐴) = 0 ↔ 𝐴 = 0)) | ||
Theorem | rpsqrtcl 15271 | The square root of a positive real is a positive real. (Contributed by NM, 22-Feb-2008.) |
⊢ (𝐴 ∈ ℝ+ → (√‘𝐴) ∈ ℝ+) | ||
Theorem | sqrtdiv 15272 | Square root distributes over division. (Contributed by Mario Carneiro, 5-May-2016.) |
⊢ (((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) ∧ 𝐵 ∈ ℝ+) → (√‘(𝐴 / 𝐵)) = ((√‘𝐴) / (√‘𝐵))) | ||
Theorem | sqrtneglem 15273 | The square root of a negative number. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (((i · (√‘𝐴))↑2) = -𝐴 ∧ 0 ≤ (ℜ‘(i · (√‘𝐴))) ∧ (i · (i · (√‘𝐴))) ∉ ℝ+)) | ||
Theorem | sqrtneg 15274 | The square root of a negative number. (Contributed by Mario Carneiro, 9-Jul-2013.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘-𝐴) = (i · (√‘𝐴))) | ||
Theorem | sqrtsq2 15275 | Relationship between square root and squares. (Contributed by NM, 31-Jul-1999.) (Revised by Mario Carneiro, 29-May-2016.) |
⊢ (((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) ∧ (𝐵 ∈ ℝ ∧ 0 ≤ 𝐵)) → ((√‘𝐴) = 𝐵 ↔ 𝐴 = (𝐵↑2))) | ||
Theorem | sqrtsq 15276 | Square root of square. (Contributed by NM, 14-Jan-2006.) (Revised by Mario Carneiro, 29-May-2016.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘(𝐴↑2)) = 𝐴) | ||
Theorem | sqrtmsq 15277 | Square root of square. (Contributed by NM, 2-Aug-1999.) (Revised by Mario Carneiro, 29-May-2016.) |
⊢ ((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘(𝐴 · 𝐴)) = 𝐴) | ||
Theorem | sqrt1 15278 | The square root of 1 is 1. (Contributed by NM, 31-Jul-1999.) |
⊢ (√‘1) = 1 | ||
Theorem | sqrt4 15279 | The square root of 4 is 2. (Contributed by NM, 3-Aug-1999.) |
⊢ (√‘4) = 2 | ||
Theorem | sqrt9 15280 | The square root of 9 is 3. (Contributed by NM, 11-May-2004.) |
⊢ (√‘9) = 3 | ||
Theorem | sqrt2gt1lt2 15281 | The square root of 2 is bounded by 1 and 2. (Contributed by Roy F. Longton, 8-Aug-2005.) (Revised by Mario Carneiro, 6-Sep-2013.) |
⊢ (1 < (√‘2) ∧ (√‘2) < 2) | ||
Theorem | sqrtm1 15282 | The imaginary unit is the square root of negative 1. A lot of people like to call this the "definition" of i, but the definition of √ df-sqrt 15242 has already been crafted with i being mentioned explicitly, and in any case it doesn't make too much sense to define a value based on a function evaluated outside its domain. A more appropriate view is to take ax-i2m1 11228 or i2 14222 as the "definition", and simply postulate the existence of a number satisfying this property. This is the approach we take here. (Contributed by Mario Carneiro, 10-Jul-2013.) |
⊢ i = (√‘-1) | ||
Theorem | nn0sqeq1 15283 | A natural number with square one is equal to one. (Contributed by Thierry Arnoux, 2-Feb-2020.) (Proof shortened by Thierry Arnoux, 6-Jun-2023.) |
⊢ ((𝑁 ∈ ℕ0 ∧ (𝑁↑2) = 1) → 𝑁 = 1) | ||
Theorem | absneg 15284 | Absolute value of the negative. (Contributed by NM, 27-Feb-2005.) |
⊢ (𝐴 ∈ ℂ → (abs‘-𝐴) = (abs‘𝐴)) | ||
Theorem | abscl 15285 | Real closure of absolute value. (Contributed by NM, 3-Oct-1999.) |
⊢ (𝐴 ∈ ℂ → (abs‘𝐴) ∈ ℝ) | ||
Theorem | abscj 15286 | The absolute value of a number and its conjugate are the same. Proposition 10-3.7(b) of [Gleason] p. 133. (Contributed by NM, 28-Apr-2005.) |
⊢ (𝐴 ∈ ℂ → (abs‘(∗‘𝐴)) = (abs‘𝐴)) | ||
Theorem | absvalsq 15287 | Square of value of absolute value function. (Contributed by NM, 16-Jan-2006.) |
⊢ (𝐴 ∈ ℂ → ((abs‘𝐴)↑2) = (𝐴 · (∗‘𝐴))) | ||
Theorem | absvalsq2 15288 | Square of value of absolute value function. (Contributed by NM, 1-Feb-2007.) |
⊢ (𝐴 ∈ ℂ → ((abs‘𝐴)↑2) = (((ℜ‘𝐴)↑2) + ((ℑ‘𝐴)↑2))) | ||
Theorem | sqabsadd 15289 | Square of absolute value of sum. Proposition 10-3.7(g) of [Gleason] p. 133. (Contributed by NM, 21-Jan-2007.) |
⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((abs‘(𝐴 + 𝐵))↑2) = ((((abs‘𝐴)↑2) + ((abs‘𝐵)↑2)) + (2 · (ℜ‘(𝐴 · (∗‘𝐵)))))) | ||
Theorem | sqabssub 15290 | Square of absolute value of difference. (Contributed by NM, 21-Jan-2007.) |
⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((abs‘(𝐴 − 𝐵))↑2) = ((((abs‘𝐴)↑2) + ((abs‘𝐵)↑2)) − (2 · (ℜ‘(𝐴 · (∗‘𝐵)))))) | ||
Theorem | absval2 15291 | Value of absolute value function. Definition 10.36 of [Gleason] p. 133. (Contributed by NM, 17-Mar-2005.) |
⊢ (𝐴 ∈ ℂ → (abs‘𝐴) = (√‘(((ℜ‘𝐴)↑2) + ((ℑ‘𝐴)↑2)))) | ||
Theorem | abs0 15292 | The absolute value of 0. (Contributed by NM, 26-Mar-2005.) (Revised by Mario Carneiro, 29-May-2016.) |
⊢ (abs‘0) = 0 | ||
Theorem | absi 15293 | The absolute value of the imaginary unit. (Contributed by NM, 26-Mar-2005.) |
⊢ (abs‘i) = 1 | ||
Theorem | absge0 15294 | Absolute value is nonnegative. (Contributed by NM, 20-Nov-2004.) (Revised by Mario Carneiro, 29-May-2016.) |
⊢ (𝐴 ∈ ℂ → 0 ≤ (abs‘𝐴)) | ||
Theorem | absrpcl 15295 | The absolute value of a nonzero number is a positive real. (Contributed by FL, 27-Dec-2007.) (Proof shortened by Mario Carneiro, 29-May-2016.) |
⊢ ((𝐴 ∈ ℂ ∧ 𝐴 ≠ 0) → (abs‘𝐴) ∈ ℝ+) | ||
Theorem | abs00 15296 | The absolute value of a number is zero iff the number is zero. Proposition 10-3.7(c) of [Gleason] p. 133. (Contributed by NM, 26-Sep-2005.) (Proof shortened by Mario Carneiro, 29-May-2016.) |
⊢ (𝐴 ∈ ℂ → ((abs‘𝐴) = 0 ↔ 𝐴 = 0)) | ||
Theorem | abs00ad 15297 | A complex number is zero iff its absolute value is zero. Deduction form of abs00 15296. (Contributed by David Moews, 28-Feb-2017.) |
⊢ (𝜑 → 𝐴 ∈ ℂ) ⇒ ⊢ (𝜑 → ((abs‘𝐴) = 0 ↔ 𝐴 = 0)) | ||
Theorem | abs00bd 15298 | If a complex number is zero, its absolute value is zero. Converse of abs00d 15453. One-way deduction form of abs00 15296. (Contributed by David Moews, 28-Feb-2017.) |
⊢ (𝜑 → 𝐴 = 0) ⇒ ⊢ (𝜑 → (abs‘𝐴) = 0) | ||
Theorem | absreimsq 15299 | Square of the absolute value of a number that has been decomposed into real and imaginary parts. (Contributed by NM, 1-Feb-2007.) |
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((abs‘(𝐴 + (i · 𝐵)))↑2) = ((𝐴↑2) + (𝐵↑2))) | ||
Theorem | absreim 15300 | Absolute value of a number that has been decomposed into real and imaginary parts. (Contributed by NM, 14-Jan-2006.) |
⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (abs‘(𝐴 + (i · 𝐵))) = (√‘((𝐴↑2) + (𝐵↑2)))) |
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