Question

Where did this 10x^2 come from?

Answer 1

See below

Explanation:

Above in the answer where yous see 5
`x^(2)`. You are multiplying that by

3x - 2

5
`x^(2)` ( 3x - 2) = 15
`x^(3)` - 10
`x^(2)`

Then you are subtracting that from the row above so it changes to

-15
`x^(3)` + 10
`x^(2)`

Answer 2

Explanation:

The 10x is just a placement in the synthetic division to get rid of the -7^2 making the 3x^. Its just placement to finish the problem