Question

How do you simplify `(x+ 3)(x-4)-5x(x+2)`?

Answer 1

`"By expansion......."`

Explanation:

`(x+3)(x-4)=x^2-x-12`

`-5x(x+2)=-5x^2-10x`

And thus `(x+3)(x-4)-5x(x+2)=`

`(x^2-x-12)-(-5x^2-10x)`

`6x^2+9x-12=3(2x^2+3x-4)`