Question

Which function has real zeros at x = 3 and x = 7?

A. f(x) = x2 + 4x – 21
B. f(x) = x2 - 4x - 21
C. f(x) = x2 - 10x + 21
D. f(x) = x² – 10x - 21

Answer 1

C

Explanation:

3^2-10(3)+21=0

7^2-10(7)+21=0

Answer 2

C. f(x) = x² - 10x + 21

Explanation:

Let f(x) = 3

=> 3² - 10(3) +21

=>9 - 30 + 21

=> 30 - 30

=> 0