Expand and simplify (x-7) (x+3)

X (x+3) - 7 (x+3)

x2+3x-7x-21

x^2-4x-21

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