If $2(a^2+b^2)=(a+b)^2$ then,

b = 2a a = -b a = b a = 2b

a = b

If $2(a^2+b^2)=(a+b)^2$ Then put the value of a and b = 1 $2(1^2+1^2)=(1+1)^2$ = 4 = 4 So satisfy from the options by putting the value of a and b = 1 If we choose a = b this will satisfy the equation.