Question

What polynomial must be subtracted from 2x^3 − x^2 + 4x − 5 so that the difference is

x^3 + 2x − 9?

Answer 1

-x^3 + x^2 - 2x - 4

Explanation:

You have to subtract

Let o = the polynomial

So you know 2x^3 - x^2 + 4x + 5 - o = x^3 + 2x - 9

Now you do 2x^3 - x^3 = x^3

then you -x^2 + answer = 0

you need to cancel it out

to cancel, you found out that it is x^2

Now you need to make from 4x to 2x.

To do that, you do 4x - 2x and you get 2x

Lastly you need to change -5 to 9. To do that you add -4.

Now since it is subtraction you have to distribute

2x^3 - x^2 + 4x - 5 -(x^3 - x^2 + 2x + 4)

= 2x^3 - x^2 + 4x + 5 - x^3 + x^2 -2x -4

= x^3 -2x + 9