# How do you factor 81x^2 – 36x + 4?

Mar 18, 2018

$81 {x}^{2} - 36 x + 4 = {\left(9 x - 2\right)}^{2}$

#### Explanation:

This is a perfect square trinomial in the form:

${A}^{2} - 2 A B + {B}^{2} = {\left(A - B\right)}^{2}$

as we can see:

$81 {x}^{2} - 36 x + 4 = {\left(9 x\right)}^{2} - 2 \left(9 x\right) \left(2\right) + {2}^{2} = {\left(9 x - 2\right)}^{2}$