Solve the equation x^2-9x+20=0

First, we need to factorise the equation on the left hand side, this can be done by finding two numbers that add together to make the 'b' coefficient (-9) and multiply to make the 'c' coefficient (20).

This will give -5 and -4. Therefore, (x-5)(x-4)=0. So, either (x-5)=0, or (x-4)=0 Giving x=5 or x=4 as the final answers.