Could you please explain #10 no calculator practice test 9


My apologies that this sat in my inbox for a few days! Summer, ya know?

The key to this question is remembering that the corresponding coefficients of equivalent polynomials will be equal. Let’s look at the given equation:


The left side isn’t in expanded form but once it is, we know that the coefficients of the x^3 terms on each side will be equal, and the coefficients of the x^2 terms will be equal, etc. So let’s expand.


Now figure out the coefficients of each power of x


Here’s where we get to apply the rule I linked to above. We now know that:




and of course 12=12.

The first equation gives us a=4, use either of the other two to solve for b:


Now that you know a=4 and b=6, you know ab=24.

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