Factorise and solve x^2 - 8x + 15 = 0

Look for factors of 15 then when adding together equal -8. A solution to this is -5 and -3 as -5 x -3=15 and (-5)+(-3)=-8 . Therefore the factors of the quadratic are (x-5) and (x-3). Make (x-5)(x-3)=0 so both brackets can equal 0 for this to be the case. As a result, x=5 and x=3