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If (x - y) = √20 and (x + y) = √12 what is the value of x^2 – y^2 ? (
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05 Jan 2022, 06:08
05 Jan 2022, 06:08
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Question Stats:
34% (00:56) correct
65% (02:17) wrong based on 35 sessions
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If (x - y) = √20 and (x + y) = √12 what is the value of x² – y² ?
(A) 2√15
(B) 4√15
(C) 3√20
(D) 6√12
(E) 2√21
(A) 2√15
(B) 4√15
(C) 3√20
(D) 6√12
(E) 2√21
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Re: If (x - y) = √20 and (x + y) = √12 what is the value of x^2 – y^2 ? (
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05 Jan 2022, 06:16
05 Jan 2022, 06:16
1
Carcass wrote:
If (x - y) = √20 and (x + y) = √12 what is the value of x² – y² ?
(A) 2√15
(B) 4√15
(C) 3√20
(D) 6√12
(E) 2√21
(A) 2√15
(B) 4√15
(C) 3√20
(D) 6√12
(E) 2√21
First recognize that we can factor the difference of squares as follows: \(x^2 – y^2 = (x+y)(x-y)\)
Now substitute the given values to get: \(x^2 – y^2 = (\sqrt{12})(\sqrt{20})\)
Simplify the given roots: \(x^2 – y^2 = (2\sqrt{3})(2\sqrt{5})\)
Multiply to get: \(x^2 – y^2 = 4\sqrt{15}\)
Answer: B
gmatclubot
Re: If (x - y) = √20 and (x + y) = √12 what is the value of x^2 – y^2 ? ( [#permalink]
05 Jan 2022, 06:16
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