I need help with question number 3

Hey there! I'd be delighted to help you out!
First, let's write down our expression!
[tex](x^2-x)+(8x-2x^2)[/tex]
When we look at this expression, we see that all of the numbers are terms, or numbers that are added. We have four terms in this equation, which are:
[tex]x^2, -x, 8x, -2x^2[/tex]
Now, to simplify, we want to combine like terms. Like terms are numbers that have the same variable (or no variable) and are raised to the same power. 1 and 5 are like terms because they both have no variable and they are both raised to the power of 1 (any number that is itself is raised to this power). 4x and 12x are like terms because they both have an x and a power of 1. 4y and 5x are not like terms because they have different variables. 4x³ and 2x² are not like terms because they are raised to different powers.
Now, we see that with our numbers, x² and -2x² are like terms, and -x and 8x are also like terms. We can combine accordingly.
[tex]x^2-2x^2=-x^2\\\\-x+8x=7x[/tex]
Now we combine to get our simplified expression!
[tex]-x^2+7x[/tex]
I hope that this helps! Have a wonderful day!