x^3 (I'm not sure how to use subscripts, sorry) + 2^3 = 13.
Since we have 2^3, solve for that:
2^3 = 2*2*2 = 8
Now, substitute 2^3 for 8 (x^3 + 8 = 13).
Subtract 8 from both sides of the equation, and now you are left with x^3 = 5.
To find x, you now need to find the cubed root of 5, and then you have your answer for x.
Cubed root of 5 = about 1.7, so 1.7 = x.
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To make sure you got the right answer (or close enough to it, 1.7 is not the exact answer for cubed root of 5, so you might not get a perfect 13), plug 1.7 (x) back into the equation:
1.7^3 + 2^3 = 12.913, which is close enough to 13. If you put down x = 1.7, it would be counted as a correct answer.
