Question

Which are cubic functions? Check all that apply.

f(x) = –4 – 2x + 5x3
f(x) = –3x – 1
f(x) = –x2 + 5x – x3
f(x) = x2 – 6x3 + 2x4 + 1
f(x) = 2x3 + 3x2 – x – 3
f(x) = 3x2 – 1 – 8x

Answer 1

Cubic functions are those whose highest power of x is 3. The cubic ones are:

- f(x) = –4 – 2x + 5x^3
- f(x) = –x^2 + 5x – x^3
- f(x) = 2x^3 + 3x^2 – x – 3

The others are not cubic (they have highest degree 1, 2, or 4).