Question

How do you multiply `(7n + 8) ( 9n ^ { 3} - 6n ^ { 2} + 2n - 9)`?

Answer 1

First multiply the first part of the first term with everything in the second term, and then again for the second part of the first term:

Explanation:

`=7n*(9n^3-6n^2+2n-9)+8*(9n^3-6n^2+2n-9)`

`=(63n^4-42n^3+14n^2-63n)+(72n^3-48n^2+16n-72)`

Now, add like powers of `n`:

`=63n^4+(-42+72)n^3+(14-48)n^2+(-63+16)n-72`

`=63n^4+30n^3-34n^2-47n-72`