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GMATPrepNow
If xy = 7 and x – y = 7, then x² + y² =

(A) 35
(B) 42
(C) 49
(D) 56
(E) 63

* Kudos for all correct solutions
x² + y²=(x-y)²+2xy
=7²+2*7
=49+14
=63
So, the correct choice is
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GMATPrepNow
If xy = 7 and x – y = 7, then x² + y² =

(A) 35
(B) 42
(C) 49
(D) 56
(E) 63

* Kudos for all correct solutions

\(( x - y )^2 + 2xy = x^2 + y^2\)

Or, \(7^2 + 2*7 = x^2 + y^2\)

Or, \(49 + 14 = x^2 + y^2\)

Or, \(x^2 + y^2 = 63\)

Thus, answer must be (E) 63...
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If xy = 7 and x – y = 7, then x² + y² =

\((x - y)^2 = x^2 - 2xy + y^2\)

\(x^2 + y^2 = (x - y)^2 + 2xy\)

\(x^2 + y^2 = (7)^2 + 2 * 7\)

\(x^2 + y^2 = 49 + 14\)

\(x^2 + y^2 = 63\)

Hence, Answer is E

Did you like the answer? 1 Kudos Please :good
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BrentGMATPrepNow
If xy = 7 and x – y = 7, then x² + y² =

(A) 35
(B) 42
(C) 49
(D) 56
(E) 63

* Kudos for all correct solutions

Asked: If xy = 7 and x – y = 7, then x² + y² =

\((x - y)^2 = x^2 + y^2 -2xy\)
\(49 = x^2 + y^2 - 14\)
\(x^2 + y^2 = 49 + 14 = 63\)

IMO E
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BrentGMATPrepNow
If xy = 7 and x – y = 7, then x² + y² =

(A) 35
(B) 42
(C) 49
(D) 56
(E) 63

* Kudos for all correct solutions

\(x^2 + y^2 = (x - y)^2 + 2xy\)

Or, \(x^2 + y^2 = 7^2 + 2*7\)

Or, \(x^2 + y^2 = 49 + 14\)

Or, \(x^2 + y^2 = 63\), Answer must be (E)
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