SOLUTION: please help me graph x^2+3x=18

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Question 142111: please help me graph x^2+3x=18
Answer by nabla(475) About Me  (Show Source):
You can put this solution on YOUR website!
To graph a quadratic equation, it is first instructive to solve it; find its zeros:
x%5E2%2B3x=18
x%5E2%2B3x-18=0
%28x%2B6%29%28x-3%29=0
Gives x=-6 or x=3.
(Check: 36-18=18; 18=18 correct; 9+9=18; 18=18 correct)
Now, those two values give you x-intercepts to a function f(x)=x^2+3x-18.
The function's graph is as follows:
graph%28+300%2C+200%2C+-10%2C+10%2C+-20%2C+20%2C+x%5E2%2B3x-18+%29