Question

How do you combine `(x^2-bx-7) - (3x^2+2x-4)`?

Answer 1

Group by like powers of `x` and perform standard arithmetic to get:
`color(white)("XXXX")` `-2x^2-(b+2)x -3`

Explanation:

`(x^2−bx−7)−(3x^2+2x−4)`
`color(white)("XXXX")`Regroup as:
`(x^2-3x^2) + (-bx -2x) + (-7 -(-4))`

`=-2x^2 -(b+2)x -3`

Answer 2

`(x^2-bx-7)-(3x^2+2x-4)=-2x^2-bx-2x-3`

Explanation:

`(x^2-bx-7)-(3x^2+2x-4)`

Distribute the negative sign to each of the terms inside the second set of parentheses, then remove the parentheses.

`x^2-bx-7-3x^2-2x+4`

Group like terms.

`x^2-3x^2-bx-2x-7+4`

Combine.

`-2x^2-bx-2x-3`