SOLUTION: using the quadratic equation x2-4x-5=0 perform the following task: solve by completing the square. how do i do this im lost thank you.

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: using the quadratic equation x2-4x-5=0 perform the following task: solve by completing the square. how do i do this im lost thank you.      Log On


   



Question 31450: using the quadratic equation x2-4x-5=0 perform the following task:
solve by completing the square.
how do i do this im lost thank you.

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by completing the square:
x%5E2-4x-5+=+0 First add 5 to both sides of the equation.
x%5E2-4x+=+5 Now complete the square in the x-terms by adding the square of half the x-coefficient (%284%2F2%29%5E2+=+4)to both sides of the equation.
x%5E2-4x%2B4+=+9 Now factor the left side.
%28x-2%29%5E2+=+9 Take the square root of both sides.
x-2+=+3orx-2+=+-3 So:
x+=+5 and/or x+=+-1
The roots are:
x+=+5
x+=+-1