How do you solve x^2-6x-25=0 by completing the square?

1 Answer
May 10, 2017

x=3+-sqrt(34)

Explanation:

First, add 25 to both sides:

x^2-6x=25

Now, add something that would make a square on the left side. Use the equation:

(b/(2a))^2

b=-6 and a=1. Plugging in gives:

(-6/2)^2=9

Add 9 to both sides:

x^2-6x+9=25+9

The left side becomes:

(x-3)^2=34

Square root both sides:

x-3=+-sqrt(34)

Now add 3 to both sides:

x=3+-sqrt(34)