How do you divide ( -3x^3+ 12x^2-14x-6 )/(x + 1 )?

1 Answer

color(blue)((-3x^3+12x^2-14x-6)/(x+1)=-3x^2+15x-29+23/(x+1))

Explanation:

From the given (-3x^3+12x^2-14x-6)/(x+1)

We have our
dividend -3x^3+12x^2-14x-6
divisor x+1

Let us begin the

color(red)("Long Division Method")

" " " " " "underline(-3x^2+15x-29)larrthe quotient
x+1|~-3x^3+12x^2-14x-6
" " " " " "underline(-3x^3-3x^2" " " " " " " " " " ")
" " " " " " " " " 0"" +15x^2-14x-6
" " " " " " " " " " " "underline(15x^2+15x" " " " ")
" " " " " " " " " " " " " "0"" -29x-6
" " " " " " " " " " " " " " " " underline(-29x-29)
" " " " " " " " " " " " " " " " " " " 0""+23 larrthe remainder

We write our final answer

(-3x^3+12x^2-14x-6)/(x+1)=-3x^2+15x-29+23/(x+1)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

color(red)("Another method is by Synthetic Division")

Our trial divisor comes from the divisor x+1. Simply equate this to zero

x+1=0 and x=-1

Use the numerical coefficients of the dividend

" "x^3" " " "" "x^2" " " " " "x^1" " " " " "x^0

-3" " " "+12" " " "-14" " " "-6" " "|~-1larrtrial divisor
underline(" " " " " " " "+3" " " "-15" " " "+29" " )
-3" " " "+15" " " "-29" " " "+23larr the remainder

The last set of numbers -3, +15, -29 are the numerical coefficients of x^2, x^1, x^0 repectively so that our quotient is

-3x^2+15x-29

since the remainder is +23, we write the last term (+23)/(x+1)

Our final answer is

(-3x^3+12x^2-14x-6)/(x+1)=-3x^2+15x-29+23/(x+1)

God bless....I hope the explanation is useful.