How do you factor 144x²-81?

2 Answers
May 23, 2016

This is of the form a^2-b^2, since both 144 and 81 are squares

Explanation:

We can even take out 9 and still have squares:
=9xx16x^2-9xx3^2=9(16x^2-9)

=9(4^2xxx^2-3^2)=9((4x)^2-3^2)

Since a^2-b^2harr(a+b)(a-b):

=9(4x+3)(4x-3)

May 23, 2016

9(4x-3)(4x+3)

Explanation:

9(16x^2-9)

This can then be simplified to:

9(4x-3)(4x+3) using the difference of two squares rule.

Therefore, x=±3/4

Or, you could solve for x like this:

144x^2-81

144x^2=81

x^2=81/144

x=±sqrt(81/144)

x= 3/4

x=-3/4