Question

A function f(x) has x-intercepts of -3 and -5. What is the constant term in the function?

f(x) = x2 + 8x +

Answer 1

15

Explanation:

The x-intercepts -3 and -5 are also "roots" of the polynomial. The corresponding factors are (x + 3) and (x + 5). Multiply the constants together: 3*5 = 15. This is the desired constant term.

Note that your f(x) = x2 + 8x + should be written f(x) = x^2 + 8x + ... The " ^ " denotes exponentiation.

Check: Multiply (x + 3) and (x + 5) together and compare the result to the given polynomial with constant term 15:

f(x) = (x + 3)(x + 5) = x^2 + 3x + 5x + 15 = x^2 + 8x + 15. This matches!