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Theorem List for Metamath Proof Explorer - 14601-14700   *Has distinct variable group(s)
TypeLabelDescription
Statement

Theoremrennim 14601 A real number does not lie on the negative imaginary axis. (Contributed by Mario Carneiro, 8-Jul-2013.)
(𝐴 ∈ ℝ → (i · 𝐴) ∉ ℝ+)

Theoremcnpart 14602 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+)))

Theoremsqr0lem 14603 Square root of zero. (Contributed by Mario Carneiro, 9-Jul-2013.)
((𝐴 ∈ ℂ ∧ ((𝐴↑2) = 0 ∧ 0 ≤ (ℜ‘𝐴) ∧ (i · 𝐴) ∉ ℝ+)) ↔ 𝐴 = 0)

Theoremsqrt0 14604 Square root of zero. (Contributed by Mario Carneiro, 9-Jul-2013.)
(√‘0) = 0

Theoremsqrlem1 14605* Lemma for 01sqrex 14612. (Contributed by Mario Carneiro, 10-Jul-2013.)
𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴}    &   𝐵 = sup(𝑆, ℝ, < )       ((𝐴 ∈ ℝ+𝐴 ≤ 1) → ∀𝑦𝑆 𝑦 ≤ 1)

Theoremsqrlem2 14606* Lemma for 01sqrex 14612. (Contributed by Mario Carneiro, 10-Jul-2013.)
𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴}    &   𝐵 = sup(𝑆, ℝ, < )       ((𝐴 ∈ ℝ+𝐴 ≤ 1) → 𝐴𝑆)

Theoremsqrlem3 14607* Lemma for 01sqrex 14612. (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 ∀𝑦𝑆 𝑦𝑧))

Theoremsqrlem4 14608* Lemma for 01sqrex 14612. (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))

Theoremsqrlem5 14609* Lemma for 01sqrex 14612. (Contributed by Mario Carneiro, 10-Jul-2013.)
𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴}    &   𝐵 = sup(𝑆, ℝ, < )    &   𝑇 = {𝑦 ∣ ∃𝑎𝑆𝑏𝑆 𝑦 = (𝑎 · 𝑏)}       ((𝐴 ∈ ℝ+𝐴 ≤ 1) → ((𝑇 ⊆ ℝ ∧ 𝑇 ≠ ∅ ∧ ∃𝑣 ∈ ℝ ∀𝑢𝑇 𝑢𝑣) ∧ (𝐵↑2) = sup(𝑇, ℝ, < )))

Theoremsqrlem6 14610* Lemma for 01sqrex 14612. (Contributed by Mario Carneiro, 10-Jul-2013.)
𝑆 = {𝑥 ∈ ℝ+ ∣ (𝑥↑2) ≤ 𝐴}    &   𝐵 = sup(𝑆, ℝ, < )    &   𝑇 = {𝑦 ∣ ∃𝑎𝑆𝑏𝑆 𝑦 = (𝑎 · 𝑏)}       ((𝐴 ∈ ℝ+𝐴 ≤ 1) → (𝐵↑2) ≤ 𝐴)

Theoremsqrlem7 14611* Lemma for 01sqrex 14612. (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 ∣ ∃𝑎𝑆𝑏𝑆 𝑦 = (𝑎 · 𝑏)}       ((𝐴 ∈ ℝ+𝐴 ≤ 1) → (𝐵↑2) = 𝐴)

Theorem01sqrex 14612* 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))

Theoremresqrex 14613* 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))

Theoremsqrmo 14614* 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+))

Theoremresqreu 14615* 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+))

Theoremresqrtcl 14616 Closure of the square root function. (Contributed by Mario Carneiro, 9-Jul-2013.)
((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘𝐴) ∈ ℝ)

Theoremresqrtthlem 14617 Lemma for resqrtth 14618. (Contributed by Mario Carneiro, 9-Jul-2013.)
((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (((√‘𝐴)↑2) = 𝐴 ∧ 0 ≤ (ℜ‘(√‘𝐴)) ∧ (i · (√‘𝐴)) ∉ ℝ+))

Theoremresqrtth 14618 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)

Theoremremsqsqrt 14619 Square of square root. (Contributed by Mario Carneiro, 10-Jul-2013.)
((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → ((√‘𝐴) · (√‘𝐴)) = 𝐴)

Theoremsqrtge0 14620 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))

Theoremsqrtgt0 14621 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))

Theoremsqrtmul 14622 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)))

Theoremsqrtle 14623 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)) → (𝐴𝐵 ↔ (√‘𝐴) ≤ (√‘𝐵)))

Theoremsqrtlt 14624 Square root is strictly monotonic. Closed form of sqrtlti 14752. (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)))

Theoremsqrt11 14625 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))

Theoremsqrt00 14626 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))

Theoremrpsqrtcl 14627 The square root of a positive real is a positive real. (Contributed by NM, 22-Feb-2008.)
(𝐴 ∈ ℝ+ → (√‘𝐴) ∈ ℝ+)

Theoremsqrtdiv 14628 Square root distributes over division. (Contributed by Mario Carneiro, 5-May-2016.)
(((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) ∧ 𝐵 ∈ ℝ+) → (√‘(𝐴 / 𝐵)) = ((√‘𝐴) / (√‘𝐵)))

Theoremsqrtneglem 14629 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+))

Theoremsqrtneg 14630 The square root of a negative number. (Contributed by Mario Carneiro, 9-Jul-2013.)
((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘-𝐴) = (i · (√‘𝐴)))

Theoremsqrtsq2 14631 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) = 𝐵𝐴 = (𝐵↑2)))

Theoremsqrtsq 14632 Square root of square. (Contributed by NM, 14-Jan-2006.) (Revised by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘(𝐴↑2)) = 𝐴)

Theoremsqrtmsq 14633 Square root of square. (Contributed by NM, 2-Aug-1999.) (Revised by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (√‘(𝐴 · 𝐴)) = 𝐴)

Theoremsqrt1 14634 The square root of 1 is 1. (Contributed by NM, 31-Jul-1999.)
(√‘1) = 1

Theoremsqrt4 14635 The square root of 4 is 2. (Contributed by NM, 3-Aug-1999.)
(√‘4) = 2

Theoremsqrt9 14636 The square root of 9 is 3. (Contributed by NM, 11-May-2004.)
(√‘9) = 3

Theoremsqrt2gt1lt2 14637 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)

Theoremsqrtm1 14638 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 14597 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 10604 or i2 13573 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)

Theoremnn0sqeq1 14639 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)

Theoremabsneg 14640 Absolute value of the opposite. (Contributed by NM, 27-Feb-2005.)
(𝐴 ∈ ℂ → (abs‘-𝐴) = (abs‘𝐴))

Theoremabscl 14641 Real closure of absolute value. (Contributed by NM, 3-Oct-1999.)
(𝐴 ∈ ℂ → (abs‘𝐴) ∈ ℝ)

Theoremabscj 14642 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))

Theoremabsvalsq 14643 Square of value of absolute value function. (Contributed by NM, 16-Jan-2006.)
(𝐴 ∈ ℂ → ((abs‘𝐴)↑2) = (𝐴 · (∗‘𝐴)))

Theoremabsvalsq2 14644 Square of value of absolute value function. (Contributed by NM, 1-Feb-2007.)
(𝐴 ∈ ℂ → ((abs‘𝐴)↑2) = (((ℜ‘𝐴)↑2) + ((ℑ‘𝐴)↑2)))

Theoremsqabsadd 14645 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))))))

Theoremsqabssub 14646 Square of absolute value of difference. (Contributed by NM, 21-Jan-2007.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((abs‘(𝐴𝐵))↑2) = ((((abs‘𝐴)↑2) + ((abs‘𝐵)↑2)) − (2 · (ℜ‘(𝐴 · (∗‘𝐵))))))

Theoremabsval2 14647 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))))

Theoremabs0 14648 The absolute value of 0. (Contributed by NM, 26-Mar-2005.) (Revised by Mario Carneiro, 29-May-2016.)
(abs‘0) = 0

Theoremabsi 14649 The absolute value of the imaginary unit. (Contributed by NM, 26-Mar-2005.)
(abs‘i) = 1

Theoremabsge0 14650 Absolute value is nonnegative. (Contributed by NM, 20-Nov-2004.) (Revised by Mario Carneiro, 29-May-2016.)
(𝐴 ∈ ℂ → 0 ≤ (abs‘𝐴))

Theoremabsrpcl 14651 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+)

Theoremabs00 14652 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))

Theoremabs00ad 14653 A complex number is zero iff its absolute value is zero. Deduction form of abs00 14652. (Contributed by David Moews, 28-Feb-2017.)
(𝜑𝐴 ∈ ℂ)       (𝜑 → ((abs‘𝐴) = 0 ↔ 𝐴 = 0))

Theoremabs00bd 14654 If a complex number is zero, its absolute value is zero. Converse of abs00d 14809. One-way deduction form of abs00 14652. (Contributed by David Moews, 28-Feb-2017.)
(𝜑𝐴 = 0)       (𝜑 → (abs‘𝐴) = 0)

Theoremabsreimsq 14655 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)))

Theoremabsreim 14656 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))))

Theoremabsmul 14657 Absolute value distributes over multiplication. Proposition 10-3.7(f) of [Gleason] p. 133. (Contributed by NM, 11-Oct-1999.) (Revised by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (abs‘(𝐴 · 𝐵)) = ((abs‘𝐴) · (abs‘𝐵)))

Theoremabsdiv 14658 Absolute value distributes over division. (Contributed by NM, 27-Apr-2005.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ∧ 𝐵 ≠ 0) → (abs‘(𝐴 / 𝐵)) = ((abs‘𝐴) / (abs‘𝐵)))

Theoremabsid 14659 A nonnegative number is its own absolute value. (Contributed by NM, 11-Oct-1999.) (Revised by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℝ ∧ 0 ≤ 𝐴) → (abs‘𝐴) = 𝐴)

Theoremabs1 14660 The absolute value of one is one. (Contributed by David A. Wheeler, 16-Jul-2016.)
(abs‘1) = 1

Theoremabsnid 14661 A negative number is the negative of its own absolute value. (Contributed by NM, 27-Feb-2005.)
((𝐴 ∈ ℝ ∧ 𝐴 ≤ 0) → (abs‘𝐴) = -𝐴)

Theoremleabs 14662 A real number is less than or equal to its absolute value. (Contributed by NM, 27-Feb-2005.)
(𝐴 ∈ ℝ → 𝐴 ≤ (abs‘𝐴))

Theoremabsor 14663 The absolute value of a real number is either that number or its negative. (Contributed by NM, 27-Feb-2005.)
(𝐴 ∈ ℝ → ((abs‘𝐴) = 𝐴 ∨ (abs‘𝐴) = -𝐴))

Theoremabsre 14664 Absolute value of a real number. (Contributed by NM, 17-Mar-2005.)
(𝐴 ∈ ℝ → (abs‘𝐴) = (√‘(𝐴↑2)))

Theoremabsresq 14665 Square of the absolute value of a real number. (Contributed by NM, 16-Jan-2006.)
(𝐴 ∈ ℝ → ((abs‘𝐴)↑2) = (𝐴↑2))

Theoremabsmod0 14666 𝐴 is divisible by 𝐵 iff its absolute value is. (Contributed by Jeff Madsen, 2-Sep-2009.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ+) → ((𝐴 mod 𝐵) = 0 ↔ ((abs‘𝐴) mod 𝐵) = 0))

Theoremabsexp 14667 Absolute value of positive integer exponentiation. (Contributed by NM, 5-Jan-2006.)
((𝐴 ∈ ℂ ∧ 𝑁 ∈ ℕ0) → (abs‘(𝐴𝑁)) = ((abs‘𝐴)↑𝑁))

Theoremabsexpz 14668 Absolute value of integer exponentiation. (Contributed by Mario Carneiro, 6-Apr-2015.)
((𝐴 ∈ ℂ ∧ 𝐴 ≠ 0 ∧ 𝑁 ∈ ℤ) → (abs‘(𝐴𝑁)) = ((abs‘𝐴)↑𝑁))

Theoremabssq 14669 Square can be moved in and out of absolute value. (Contributed by Scott Fenton, 18-Apr-2014.) (Proof shortened by Mario Carneiro, 29-May-2016.)
(𝐴 ∈ ℂ → ((abs‘𝐴)↑2) = (abs‘(𝐴↑2)))

Theoremsqabs 14670 The squares of two reals are equal iff their absolute values are equal. (Contributed by NM, 6-Mar-2009.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((𝐴↑2) = (𝐵↑2) ↔ (abs‘𝐴) = (abs‘𝐵)))

Theoremabsrele 14671 The absolute value of a complex number is greater than or equal to the absolute value of its real part. (Contributed by NM, 1-Apr-2005.)
(𝐴 ∈ ℂ → (abs‘(ℜ‘𝐴)) ≤ (abs‘𝐴))

Theoremabsimle 14672 The absolute value of a complex number is greater than or equal to the absolute value of its imaginary part. (Contributed by NM, 17-Mar-2005.) (Proof shortened by Mario Carneiro, 29-May-2016.)
(𝐴 ∈ ℂ → (abs‘(ℑ‘𝐴)) ≤ (abs‘𝐴))

Theoremmax0add 14673 The sum of the positive and negative part functions is the absolute value function over the reals. (Contributed by Mario Carneiro, 24-Aug-2014.)
(𝐴 ∈ ℝ → (if(0 ≤ 𝐴, 𝐴, 0) + if(0 ≤ -𝐴, -𝐴, 0)) = (abs‘𝐴))

Theoremabsz 14674 A real number is an integer iff its absolute value is an integer. (Contributed by Jeff Madsen, 2-Sep-2009.) (Proof shortened by Mario Carneiro, 29-May-2016.)
(𝐴 ∈ ℝ → (𝐴 ∈ ℤ ↔ (abs‘𝐴) ∈ ℤ))

Theoremnn0abscl 14675 The absolute value of an integer is a nonnegative integer. (Contributed by NM, 27-Feb-2005.) (Proof shortened by Mario Carneiro, 29-May-2016.)
(𝐴 ∈ ℤ → (abs‘𝐴) ∈ ℕ0)

Theoremzabscl 14676 The absolute value of an integer is an integer. (Contributed by Stefan O'Rear, 24-Sep-2014.)
(𝐴 ∈ ℤ → (abs‘𝐴) ∈ ℤ)

Theoremabslt 14677 Absolute value and 'less than' relation. (Contributed by NM, 6-Apr-2005.) (Revised by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((abs‘𝐴) < 𝐵 ↔ (-𝐵 < 𝐴𝐴 < 𝐵)))

Theoremabsle 14678 Absolute value and 'less than or equal to' relation. (Contributed by NM, 6-Apr-2005.) (Revised by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((abs‘𝐴) ≤ 𝐵 ↔ (-𝐵𝐴𝐴𝐵)))

Theoremabssubne0 14679 If the absolute value of a complex number is less than a real, its difference from the real is nonzero. (Contributed by NM, 2-Nov-2007.) (Proof shortened by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℝ ∧ (abs‘𝐴) < 𝐵) → (𝐵𝐴) ≠ 0)

Theoremabsdiflt 14680 The absolute value of a difference and 'less than' relation. (Contributed by Paul Chapman, 18-Sep-2007.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((abs‘(𝐴𝐵)) < 𝐶 ↔ ((𝐵𝐶) < 𝐴𝐴 < (𝐵 + 𝐶))))

Theoremabsdifle 14681 The absolute value of a difference and 'less than or equal to' relation. (Contributed by Paul Chapman, 18-Sep-2007.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → ((abs‘(𝐴𝐵)) ≤ 𝐶 ↔ ((𝐵𝐶) ≤ 𝐴𝐴 ≤ (𝐵 + 𝐶))))

Theoremelicc4abs 14682 Membership in a symmetric closed real interval. (Contributed by Stefan O'Rear, 16-Nov-2014.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ) → (𝐶 ∈ ((𝐴𝐵)[,](𝐴 + 𝐵)) ↔ (abs‘(𝐶𝐴)) ≤ 𝐵))

Theoremlenegsq 14683 Comparison to a nonnegative number based on comparison to squares. (Contributed by NM, 16-Jan-2006.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 0 ≤ 𝐵) → ((𝐴𝐵 ∧ -𝐴𝐵) ↔ (𝐴↑2) ≤ (𝐵↑2)))

Theoremreleabs 14684 The real part of a number is less than or equal to its absolute value. Proposition 10-3.7(d) of [Gleason] p. 133. (Contributed by NM, 1-Apr-2005.)
(𝐴 ∈ ℂ → (ℜ‘𝐴) ≤ (abs‘𝐴))

Theoremrecval 14685 Reciprocal expressed with a real denominator. (Contributed by Mario Carneiro, 1-Apr-2015.)
((𝐴 ∈ ℂ ∧ 𝐴 ≠ 0) → (1 / 𝐴) = ((∗‘𝐴) / ((abs‘𝐴)↑2)))

Theoremabsidm 14686 The absolute value function is idempotent. (Contributed by NM, 20-Nov-2004.)
(𝐴 ∈ ℂ → (abs‘(abs‘𝐴)) = (abs‘𝐴))

Theoremabsgt0 14687 The absolute value of a nonzero number is positive. (Contributed by NM, 1-Oct-1999.) (Proof shortened by Mario Carneiro, 29-May-2016.)
(𝐴 ∈ ℂ → (𝐴 ≠ 0 ↔ 0 < (abs‘𝐴)))

Theoremnnabscl 14688 The absolute value of a nonzero integer is a positive integer. (Contributed by Paul Chapman, 21-Mar-2011.) (Proof shortened by Andrew Salmon, 25-May-2011.)
((𝑁 ∈ ℤ ∧ 𝑁 ≠ 0) → (abs‘𝑁) ∈ ℕ)

Theoremabssub 14689 Swapping order of subtraction doesn't change the absolute value. (Contributed by NM, 1-Oct-1999.) (Proof shortened by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (abs‘(𝐴𝐵)) = (abs‘(𝐵𝐴)))

Theoremabssubge0 14690 Absolute value of a nonnegative difference. (Contributed by NM, 14-Feb-2008.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐴𝐵) → (abs‘(𝐵𝐴)) = (𝐵𝐴))

Theoremabssuble0 14691 Absolute value of a nonpositive difference. (Contributed by FL, 3-Jan-2008.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐴𝐵) → (abs‘(𝐴𝐵)) = (𝐵𝐴))

Theoremabsmax 14692 The maximum of two numbers using absolute value. (Contributed by NM, 7-Aug-2008.)
((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → if(𝐴𝐵, 𝐵, 𝐴) = (((𝐴 + 𝐵) + (abs‘(𝐴𝐵))) / 2))

Theoremabstri 14693 Triangle inequality for absolute value. Proposition 10-3.7(h) of [Gleason] p. 133. (Contributed by NM, 7-Mar-2005.) (Proof shortened by Mario Carneiro, 29-May-2016.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (abs‘(𝐴 + 𝐵)) ≤ ((abs‘𝐴) + (abs‘𝐵)))

Theoremabs3dif 14694 Absolute value of differences around common element. (Contributed by FL, 9-Oct-2006.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ∧ 𝐶 ∈ ℂ) → (abs‘(𝐴𝐵)) ≤ ((abs‘(𝐴𝐶)) + (abs‘(𝐶𝐵))))

Theoremabs2dif 14695 Difference of absolute values. (Contributed by Paul Chapman, 7-Sep-2007.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → ((abs‘𝐴) − (abs‘𝐵)) ≤ (abs‘(𝐴𝐵)))

Theoremabs2dif2 14696 Difference of absolute values. (Contributed by Mario Carneiro, 14-Apr-2016.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (abs‘(𝐴𝐵)) ≤ ((abs‘𝐴) + (abs‘𝐵)))

Theoremabs2difabs 14697 Absolute value of difference of absolute values. (Contributed by Paul Chapman, 7-Sep-2007.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (abs‘((abs‘𝐴) − (abs‘𝐵))) ≤ (abs‘(𝐴𝐵)))

Theoremabs1m 14698* For any complex number, there exists a unit-magnitude multiplier that produces its absolute value. Part of proof of Theorem 13-2.12 of [Gleason] p. 195. (Contributed by NM, 26-Mar-2005.)
(𝐴 ∈ ℂ → ∃𝑥 ∈ ℂ ((abs‘𝑥) = 1 ∧ (abs‘𝐴) = (𝑥 · 𝐴)))

Theoremrecan 14699* Cancellation law involving the real part of a complex number. (Contributed by NM, 12-May-2005.)
((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (∀𝑥 ∈ ℂ (ℜ‘(𝑥 · 𝐴)) = (ℜ‘(𝑥 · 𝐵)) ↔ 𝐴 = 𝐵))

Theoremabsf 14700 Mapping domain and codomain of the absolute value function. (Contributed by NM, 30-Aug-2007.) (Revised by Mario Carneiro, 7-Nov-2013.)
abs:ℂ⟶ℝ

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