jmc

Question

Let f(x) = ax^6 + bx^4 - cx^2 + 3. If f(91) = 1, find f(91) + f(-91).

Accepted Answer

Since only the even exponents have non-zero coefficients, f is an even function, and we know that f(-x) = f(x). Hence f(-91) = f(91) = 1 and f(91) + f(-91) = 1+1 = 2.