Question

What is the standard form of `y= (x-3)(4x+8)-(x-4)(x+2)`?

Answer 1

Multiply long hand simplify to get:
`3x^2-2x-16`

Answer 2

`3x^2 - 2x - 16`

Explanation:

distribute the 1st 'pair' of brackets using FOIL (or any method you use).

(x-3)(4x+8) = `4x^2 + 8x -12x -24 = 4x^2 -4x - 24`

Similarly for the 2nd 'pair' of brackets.

`(x-4)(x+2) = x^2 + 2x - 4x - 8 = x^2 - 2x - 8`

now have : `4x^2 - 4x - 24 - ( x^2 - 2x - 8 )`

`= 4x^2 - 4x - 24 - x^2 + 2x + 8 = 3x^2 - 2x - 16`