Question

Show/Explain that
(3x – 4)(x + 7) = 3x + 17x – 28.

Answer 1

Explanation:

You expand the brackets:

• 
  `3x(x) =3x^(2)`

• 
  `3x(7) = 21x`

• 
  `-4(x)=-4x`

• 
  `-4(+7)=-28`

Now you simplify and collect like terms:

`3x^(2) (+21x-4x)-28`

`3x^(2) +17x-28`