# How do you multiply (j + -1k)(j + -1k)?

##### 1 Answer
Jul 6, 2017

See a solution process below:

#### Explanation:

We can rewrite this expression as:

$\left(j - k\right) \left(j - k\right) = {\left(j - k\right)}^{2}$

This is a special case of the quadratic:

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

Substituting gives:

${\left(j - k\right)}^{2} = {j}^{2} - 2 j k + {j}^{2}$