Factorise then following X^2-3x+2

(X-2) (X-1)

To do this, first you want to notice that there is no number in front of the x^2.

This will not work on its own if there is

Find 2 numbers that multiply to 2 and add to - 3

-3 is in front of the x and 2 is alone in the equation so those are the numbers you are using

-2 and - 1 are the only whole numbers that do that

-2 + - 1 = - 3

-2 * - 1 = 2