SOLUTION: How to solve this quadratic equation with the quadratic formula?: x2 + 2x = 8 So far this is what I got: -2±√-28 ----------- 2 However I'm not too sure

Algebra ->  Finance -> SOLUTION: How to solve this quadratic equation with the quadratic formula?: x2 + 2x = 8 So far this is what I got: -2±√-28 ----------- 2 However I'm not too sure      Log On


   

Question 1087553: How to solve this quadratic equation with the quadratic formula?:
x2 + 2x = 8

So far this is what I got:

-2±√-28
-----------
2

However I'm not too sure what to do next, help?
Found 2 solutions by Fombitz, MathLover1:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
There's an error in your formula,
x%5E2%2B2x-8=0
a=1
b=2
c=-8
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-2+%2B-+sqrt%28+%28-2%29%5E2-4%2A1%2A%28-8%29+%29%29%2F%282%2A1%29+
x+=+%28-2+%2B-+sqrt%28+4%2B32+%29%29%2F2+
x+=+%28-2+%2B-+sqrt%28+36+%29%29%2F2+
Take it from there and finish.

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2+%2B+2x+=+8
x%5E2+%2B+2x+-8=0...compare to ax%5E2+%2B+bx+%2Bc=0, you see that a=1, b=2, and c=-8
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ....plug in a=1, b=2, and c=-8
x+=+%28-2+%2B-+sqrt%28+2%5E2-4%2A1%2A%28-8%29+%29%29%2F%282%2A1%29+
x+=+%28-2+%2B-+sqrt%284%2B32+%29%29%2F2+
x+=+%28-2+%2B-+sqrt%2836+%29%29%2F2+
x+=+%28-2+%2B-+6%29%2F2+
solutions:
x+=+%28-2+%2B+6%29%2F2+=>x+=+2+
x+=+%28-2+-+6%29%2F2+=>x+=+-4+