Re: GRE Math Challenge #51-Then the sum of all possible solution
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23 Jul 2020, 17:58
I can't post URLs yet, but if you type "graph of 4th root of (x^3 + 6*x^2)" into Google, it will show you the graph of the function.
The graph of (x^3+6*x^2)^(1/4) shows that x can in fact be negative, the only condition that holds is that x >= -6.
This follows from the inequality x^3+6*x^2 >= 0.
So x^2*(x+6)>= 0, therefore x+6 >= 0, therefore x >= -6
Therefore, the answer should be C, as possible roots of x include 0, 3, and -2 since -2 >= 6.
Am I missing something here?