Question

If x+y=10 and xy=21,find2(x²+y²).

Answer 1

Answer:

(x + y)² = 10²

x² + y² + 2xy = 100

x² + y² + 2(21) = 100 (As, xy = 21)

x² + y² + 42 = 100

x² + y² = 100 - 42

x² + y² = 58

2(x² + y²)

= 2(58) (As, x² + y² = 58)

= 116