Question

If x + y = 13 and x2 + y2 = 89, then find xy is

A) 80 B) 169 C) 258 D) 40

Answer 1

Step-by-step explanation:

X + y = 13

Squaring on both sides

(X+ y) ^2 = 13 ^2

X^2 + y ^2 + 2xy = 169 from

Question

89 + 2xy = 169

2xy = 169 - 89

2xy =60

xy = 30