Question

if f(x) =x²-a²/x²+a² and f'(1)=1, then a=?

Answer 1

×=1
1^2-a^2/1^2+a^2=1
1^2-a^2=1^2+a^2
1-1=2a^2
0=2a^2
0=a^2
0=a