Question 1013741
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What are the real zeros of x^3+4x^2-9x-36.
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Apply grouping:


{{{x^3+4x^2-9x-36}}} = {{{(x^3+4x^2)}}} - {{{(9x+36)}}} = 


{{{x^2*(x+4)}}} - {{{9*(x+4)}}} = {{{(x^2-9)*(x+4)}}} = (x+3)*(x-3)*(x-4).


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