Prove algebraically that y=x^2-4 is symmetric with the y-axis.

Question

Please help! Thanks

Answer 1

let f(x) = x^2 - 4

f(a) = a^2 - 4
f(-a) = a^2 - 4

if for some function f(x),
f(a) = f(-a) then the function is symmetric about the y-axis
(by definition)