# How do you expand (3z - 2)^2?

Apr 9, 2017

See the entire solution process below:

#### Explanation:

To square a term of the form ${\left(a - b\right)}^{2}$ use this rule:

${\left(a - b\right)}^{2} = {a}^{2} - 2 a b + {b}^{2}$

Substitute $3 z$ for $a$ and substitute $2$ for $b$ giving:

${\left(3 z - 2\right)}^{2} = {\left(3 z\right)}^{2} - 2 \left(3 z \cdot 2\right) + {2}^{2} = 9 {z}^{2} - 12 z + 4$