# How do you solve #x^2 + 18x + 80 = 0# by completing the square?

##### 2 Answers

I found:

#### Explanation:

Start by taking

now you need a number that multiplied by

So, add and subtract NOT

take

so that you can write:

root square both sides:

So you get two solutions:

or

#### Explanation:

Given :

Complete the square:

Simplify:

Write as a squared binomial:

Move the constant to the right side

Take the square root

Move constant to the right side