Question

How do you combine `(6x ^ { 3} - 8x ^ { 2} + 7x - 9) - ( 4x ^ { 3} - 9x ^ { 2} - 7x + 8)`?

Answer 1

`2x^3+x^2+14x-17`

Explanation:

`"distribute brackets and collect like terms"`

`(6x^3-8x^2+7x-9)color(red)(-1)(4x^3-9x^2-7x+8)`

`=color(red)(6x^3)color(blue)(-8x^2)color(magenta)(+7x)color(green)(-9)color(red)(-4x^3)color(blue)(+9x^2)color(magenta)(+7x)color(green)(-8)`

`=(color(red)(6x^3-4x^3))+(color(blue)(-8x^2+9x^2))+(color(magenta)(7x+7x))+(color(green)(-9-8))`

`=2x^3+x^2+14x-17`