If a(x + y) = b(x - y) = 2ab, the the value of 2(x2 + y2) is
2 (a2 - b2)
2(a2 + b2)
4(a2 - b2)
4(a2 + b2)
D.
4(a2 + b2)
a(x + y) = b(x - y) = 2ab
a(x + y) = 2ab
2b = x + y .... (i)
b(x - y) = 2ab
2a = x - y ...(ii)
Solving (i) and (ii), we get
x = a + b, y = b - a
∴ 2(x2 + y2) = 2[(a + b)]2 + (b - a)2]
= 2[a2 + b2 + 2ab + b2 + a2 - 2ab]
= 2[2a2 + 2b2]
= 4(a2 + b2)