Question

How do you FOIL `(3x - 4)(7x + 7)`?

Answer 1

`(a+b)(c+d)=ac+ad+bc+bd`
`(3x-4)(7x+7)=3x*7x+3x*7-4*7x-4*7`
`(3x-4)(7x+7)=21x²+21x-28x-28`
`(3x-4)(7x+7)=21x²-7x-28`

You can factorize by seven : `(3x-4)(7x+7)=7(3x²-x-4)`