How do you divide #(x^4-11x^3-49x^2+899x-2506)-:(x-8)#?

1 Answer
Aug 21, 2016

#(x^4-11x^3-49x^2+899x-2506) -: (x-8)#

#= (x^3-3x^2-73x+315)+14/(x-8)#

Explanation:

You can write out the quotient term by term, adding up the partial sums as you go along. This is a form of synthetic division doing the work in your head...

#x^4-11x^3-49x^2+899x-2506#

#=(x-8)(x^3... " "# to match the leading #x^4# term

#=(x-8)(x^3-3x^2... " "# to match the #x^3# term

#=(x-8)(x^3-3x^2-73x... " "# to match the #x^2# term

#=(x-8)(x^3-3x^2-73x+315)... " "# to match the #x# term

#=(x-8)(x^3-3x^2-73x+315)+14 " "# to match the constant term

OK, some of the "in your head" arithmetic was a little challenging, e.g. #73*8=560+24=584# then #899-584=315#

We can also do this by long dividing the coefficients...

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This way you get to write down your workings as you go along.

In any case, we find:

#x^4-11x^3-49x^2+899x-2506=(x-8)(x^3-3x^2-73x+315)+14#

So:

#(x^4-11x^3-49x^2+899x-2506) -: (x-8)#

#= (x^3-3x^2-73x+315)+14/(x-8)#