Could I plz plz have help with factorising this quadratics(not using quadratic formula)

(x-3)^2=(3x+10)*(x-3) so to solve this u can simply take (x-3) over to the other side so it will; look like this
(x-3)^2/(x-3)=3x+10
then it will be x-3=3x+10
-2x=13
x=-13/2 which is -6.5