SOLUTION: I understand that this problem, x^2=8x-16 should be written like this: x^2-8x+16=0. But how do i solve this: x^2+12x=3x-18

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: I understand that this problem, x^2=8x-16 should be written like this: x^2-8x+16=0. But how do i solve this: x^2+12x=3x-18      Log On


   

Question 971174: I understand that this problem, x^2=8x-16 should be written like this:
x^2-8x+16=0.
But how do i solve this: x^2+12x=3x-18
Found 2 solutions by josh_jordan, josgarithmetic:
Answer by josh_jordan(263) About Me  (Show Source):
You can put this solution on YOUR website!
First thing you need to to is get everything on one side of the equal sign and put a zero on the other side. So,

x^2 + 12x = 3x - 18

First, subtract 3x from both sides, giving us:

x^2 + 12x - 3x = 3x - 3x - 18 -----> x^2 + 9x = -18

Next, add 18 to both sides:

x^2 + 9x + 18 = 18 - 18 -----> x^2 + 9x + 18 = 0

Now, factor the left side of the equation, giving us

(x + 6)(x + 3) = 0

Set each set of parenthesis equal to 0:

x + 6 = 0
x + 3 = 0

Solve each for x:

x = -6
x = -3

So, x = -6 and -3

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Meaning what? You want to put into general form, like the first example? You already learned the
method and the skills.

x%5E2%2B12x=3x-18
and you want in the format x%5E2%2Bbx%2Bc=0. Nothing tough to do or to know.
x%5E2%2B12x-3x%2B18=3x-3x-18%2B18
highlight%28x%5E2%2B9x%2B18=0%29

That is factorable in case you really want to SOLVE it. You can factor and then
use the Zero Product Principle.