Find the SUM of the following quadratic equation:
x^2+9x-36

Question

Find the SUM of the following quadratic equation: 
x^2+9x-36

anonymous · Answer

If you can, please explain to me how to solve it step by step

anonymous · Answer

Do you want to factor your expression?

anonymous · Answer

sum of the roots?

anonymous · Answer

The question is to find the SUM of the quadratic equation, so i'm guessing I use the quadratic formula and plug it in so I think I have to find the sum of the roots?

anonymous · Answer

Okay, well in order to do that, we need to factor the expression, first. Do you know how to do that?

anonymous · Answer

I'm not good at factoring haha but I'll take a guess (x-6)(x+6)?

anonymous · Answer

Haha close, but we need to find two numbers that multiply to give you -36 and add to give you 9. Can you come up with those numbers?

anonymous · Answer

no, because the product is x^2-36

anonymous · Answer

12 and 3?

anonymous · Answer

-3

anonymous · Answer

Yeah, it's actually -3. So we would factor it like
(x-3)(x+12), correct?

anonymous · Answer

correct!

anonymous · Answer

Okay, so now we set it equal to zero.
(x-3)(x+12) = 0
Can you tell me what two values x could be for the equation to equal 0?

anonymous · Answer

3 and -12

anonymous · Answer

That's right! Those are the roots of the equation.

anonymous · Answer

Oh wow that was easy! Thanks for explaining it for me :-)

anonymous · Answer

You're welcome! :D