Question

if x+y =10 and xy =21 ,find 2(x^2+y^2)

Answer 1

x^2+y^2 = (x+y)^2 - 2xy = 10^2 - 2×21 = 58
Therefore, 2(x^2+y^2) = 2×58 = 116

Answer 2

Step-by-step explanation:

2(x^2+y^2)

(x+y)^2=100

x^2+y^2+2xy=100

x^2+y^2+2(21)=100

x^2+y^2=58

2(x^2+y^2)=116