How do you simplify and divide #(x^3+13x^2-12x-8)/(x+2)#?

1 Answer
Jan 13, 2017

Quotient is #x^2+11x-34# and remainder is #60#

Explanation:

To divide #x^3+13x^2-12x-8# by #x+2#

One Write the coefficients of #x# in the dividend inside an upside-down division symbol.

#color(white)(1)|color(white)(X)1" "color(white)(X)13color(white)(XX)-12" "" "-8#
#color(white)(1)|" "color(white)(X)#
#" "stackrel("—————————————)#

Two As #x+2=0# gives #x=-2# put #-2# at the left.

#-2|color(white)(X)1" "color(white)(X)13color(white)(Xx)-12" "" "2#
#color(white)(xx)|" "color(white)(XX)#
#" "stackrel("—————————————)#

Three Drop the first coefficient of the dividend below the division symbol.

#-2|color(white)(X)1" "color(white)(X)13color(white)(XX)-12" "" "-8#
#color(white)(xx)|" "color(white)(X)#
#" "stackrel("—————————————)#
#color(white)(xx)|color(white)(X)color(red)1#

Four Multiply the result by the constant, and put the product in the next column.

#-2|color(white)(X)1" "color(white)(X)13color(white)(XX)-12" "" "-8#
#color(white)(xx)|" "color(white)(Xx)-2#
#" "stackrel("—————————————)#
#color(white)(xx)|color(white)(X)color(blue)1#

Five Add down the column.

#-2|color(white)(X)1" "color(white)(X)13color(white)(XX)-12" "" "-8#
#color(white)(xx)|" "color(white)(Xx)-2#
#" "stackrel("—————————————)#
#color(white)(xx)|color(white)(X)color(blue)1color(white)(X11)color(red)11#

Six Repeat Steps Four and Five until you can go no farther.

#-2|color(white)(X)1" "color(white)(X)13color(white)(XX)-12" "" -8#
#color(white)(xx)|" "color(white)(XX)-2color(white)(xx)-22color(white)(Xxx)68#
#" "stackrel("—————————————)#
#color(white)(xx)|color(white)(X)color(blue)1color(white)(X11)color(red)11color(white)(XX)color(red)(-34)color(white)(XXX)color(red)(60)#

Hence, Quotient is #x^2+11x-34# and remainder is #60#.