SOLUTION: What are the real zeros of x^3+4x^2-9x-36.

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Question 1013741: What are the real zeros of x^3+4x^2-9x-36.
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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What are the real zeros of x^3+4x^2-9x-36.
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Apply grouping:

x%5E3%2B4x%5E2-9x-36 = %28x%5E3%2B4x%5E2%29 - %289x%2B36%29 =

x%5E2%2A%28x%2B4%29 - 9%2A%28x%2B4%29 = %28x%5E2-9%29%2A%28x%2B4%29 = (x+3)*(x-3)*(x-4).

So, the roots are -3, 3 and 4.