If x+y=4 and xy =2 find the value of x square +y square???????????
we have, (x + y) = 4
squaring both sides, we get
(x + y)2 = (4)2
⇒ x2 + y2 + 2xy = 16
⇒ x2 + y2 +2(2) = 16
⇒ x2 + y2 + 4 = 16
⇒ x2 + y2 = 16 - 4
⇒ x2 + y2 = 12
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