Question

If xy =18 and x2 +y2 =85, find x+y

Answer 1

Answer:

7

Step-by-step explanation:

We know that,

(a + b)2 = a2 + 2ab + b2

(x + y)2 = x2 + 2xy + y2 = 85 + 2( - 18) = 85 - 36 = 49

(x + y)2 = 72

(x + y) = 7

∴ (x + y) = 7

Answer 2

Given ,

Xy = 18

X2 + Y2 = 85

(x+y)^2 = x2 + y2 + 2xy

(x+y)^2 = 85 + 2×18

(x+y)^2 = 85 + 36

(x+y)^2 = 121

X+Y = 11

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