If x+y=15 and x y=56, then what is the value of x²+y² ? · ABC26GN0985
Subject: General Aptitude · Chapter: Simplification · Exam: L.I.C.A.D.O. 2007
If $x+y=15$ and $x y=56$, then what is the value of $x^{2}+y^{2}$ ?
(a)110
(b)113
(c)121
(d)Cannot be determined
(e)None of these
Answer
Explanation
$x+y=15 \Rightarrow(x+y)^{2}=(15)^{2}=225$ $$\begin{aligned} & \Rightarrow x^{2}+y^{2}+2 x y=225 \\ & \Rightarrow x^{2}+y^{2}=225-2 x y=225-2 \times 56 \\ & =225-112=113 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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