Question

Which expression correctly factors the polynomial?

9x2 - 49
A. (3x – 7)?
B. (3x – 7)(3x + 7)
C. (9x + 7)(x - 7)
D. (9x - 7)(x + 7)

Answer 1

B

Explanation:

9x² - 49 ← is a difference of squares and factors in general as

a² - b² = (a - b)(a + b)

Thus

9x² - 49

= (3x)² - 7²

= (3x - 7)(3x + 7) → B