Question

Which expression is equivalent to the binomial shown below?

4x^2+9

A
(4x+9i)(x−1i)

B
(2x+3)(2x+3)

C
(2x+3i)(2x−3i)

D
(4x+9)(x+1)

Answer 1

C. (2x+3i)(2x−3i)

Explanation:

The factoring of the difference of squares is ...

a^2 - b^2 = (a + b)(a - b)

You have the difference of the squares ...

4x^2 - (-9)

= (2x)^2 - (3i)^2

so the factoring is ...

(2x +3i)(2x -3i) . . . . . . matches choice C