Question

If x²+y²=34 and xy=7.5,find the value of 5(x-y)²​

Answer 1

It is given that,

x²+y² = 34 ----(1)

xy = 10½ = 21/2 ---(2)

Value of 2(x+y)²+(x-y)²

= (x+y)² + [(x+y)²+(x-y)²]

= x²+y²+2xy + 2(x²+y²)

= 34 + 2×(21/2)+2×34

= 34 + 21 + 68

= 123