Question

What is the standard form of `y= (x+7)(2x+15)-(x-7)^2`?

Answer 1

`y=x^2+43x+56`

Explanation:

standard form is `y=ax^2+bx+c`

first multiply/distribute to expand everything:
`y=(x+7)(2x+15)-(x-7)^2`
`y=x(2x+15)+7(2x+15)-(x-7)(x-7)`
`y=2x^2+15x+14x+105-(x(x-7)-7(x-7))`
`y=2x^2+29x+105-(x^2-7x-7x+49)`

combine like terms as you go

`y=2x^2+29x+105-x^2+14x-49`
`y=x^2+43x+56`