Let f(x) = ax7 + bx3 + cx – 5, where a, b, and c are constants.
If f(-7) = 7, then what is f(7)?
- -17
- -7
- 14
- 21
- not uniquely determined
f(x) = ax7 + bx3 + cx – 5.
f(-7) = a(-7)7 + b(-7)3 + c(-7) – 5
7 = a(-7)7 + b(-7)3 + c(-7) + 5 – 10
7 = –a(7)7 – b(7)3 – c(7) -(- 5) – 10
7 = –f(7) – 10
f(7) = -10 – 7 = -17
The answer is (a).