Question

How do you factor completely `x^2– 7x + 18`?

Answer 1

The given expression does not factor. Maybe these were meant?
`x^2 -7x -18 = (x+9)(x-2)`
`x^2 -9x +18 = (x-3)(x-6)`

Explanation:

This expression does not factor- there might be a typo perhaps?

The following are possibly what was meant?

`x^2 -7x -18 = (x-9)(x+2)`
Factors of 18 which subtract to make 7, are 9 and 2.

OR

`x^2 -9x +18 = (x-3)(x-6)`
Factors of 18 which ADD to give 9 are 6 and 3

Hope this helps.