# How do you solve #x^2-8x=9# by completing the square?

##### 2 Answers

Jul 7, 2015

Solve y = x^2 - 8x - 9 = 0

#### Explanation:

In this case, you don't need to solve by completing the squares.

Use the shortcut.

When (a - b + c = 0) --> 2 real roots: (-1) and (-c/a = 9).

Jul 7, 2015

You take half the

#### Explanation:

This means you have to add

So:

Or: