How do you solve x^2-2x-14=0 by completing the square?

1 Answer
Jul 27, 2017

x= +-sqrt(15)+1

Explanation:

First, you have to move the 14 to the other side by adding it :

x^2-2x=14

To complete the square you divide the term with one x by 2 and then take that number and square it :

2/2=1 , 1^2=1

We then take that 1 and add it to both sides of the equation :

x^2-2x+1=15

Now we can factor the left side of the equation :

(x-1)^2=15

Take the square root of both sides to get rid of the square on the left hand side (be sure to add the +- on the 15) :

sqrt((x-1)^2)=+-sqrt(15)

which then equals...

x-1=+-sqrt(15)

Now get x by itself :

x= +-sqrt(15)+1