# How do you factor #4x^2 + 9#?

##### 1 Answer

Jan 15, 2017

#### Answer:

There are no simpler factors with Real coefficients, but:

#4x^2+9 = (2x-3i)(2x+3i)#

#### Explanation:

Note that

Hence

So

It is possible to factor it with Complex coefficients.

The difference of squares identity can be written:

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

In conjunction with

#4x^2+9 = (2x)^2-(3i)^2 = (2x-3i)(2x+3i)#