Hello!
To factor this, we will want to find the GCF of all of these numbers. It cannot involve x, as 18 is a constant.
x·x-9x+18
As you can see, there is no common factor, so we cannot multiply a parentheses by one number. What we can do, though, is multiply two parentheses. We can use the FOIL method, which means that to unfactor two parentheses, you multiply the first numbers, outside, inside, and last. Let's try doing so.
(a,b)(y,z)
First of all, a multiplied by x will probably have to equal x², as it appears first. This means a and x are x.
(x,b)(x,z)
As you can see, the outside and inside are both going to have an x in them. This means that we will want some numbers that will add to make -9, and will multiply to make 18. If you think about it, -3 and -6 would work.
-3+-6=-9
-3(-6)=18
Therefore, our factored answer is below.
(x-3)(x-6)
I hope this helps!
