SOLUTION: Please help me solve this equation 5-5 Completing the Square Solving a quadratic equation if the coefficient of x^2 is NOT 1 3x^2+12x-9=0

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: Please help me solve this equation 5-5 Completing the Square Solving a quadratic equation if the coefficient of x^2 is NOT 1 3x^2+12x-9=0      Log On


   

Question 191083: Please help me solve this equation
5-5 Completing the Square
Solving a quadratic equation if the coefficient of x^2 is NOT 1

3x^2+12x-9=0
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
3x^2 + 12x - 9 = 0
:
3x^2 + 12x + ___ = 9
Divide both sides by 3, makes the coefficient of x^2 to be 1
x^2 + 4x + ___ = 3
Complete the square, divide the coefficient of x by 2 and square it:
x^2 + 4x + 4 = 3 + 4
:
(x + 2)^2 = 7
:
x + 2 = +/-sqrt%287%29
x = -2 + sqrt%287%29
and
x = -2 - sqrt%287%29