It is easy. why you didn't do it yourself?. Anyway here is a tip to get simplified answer. first write x*x x^2 then multiply first x with 3 and second x with (-7) then sum up. will get 3x+(-7x) i.e (-4x). so write this. x^2+(-4x) and multiply (-7) by 3 i.e (-21) x^2-4x+(-21) So the answer will be. x^2-4x-21
