How do you divide (x^3 - 4x^2+2x - 8)/(2x^2+4x-2)x34x2+2x82x2+4x2?

2 Answers
May 17, 2017

x/2-3+(15x-14)/(2x^2+4x-2)x23+15x142x2+4x2

Explanation:

" "x^3-4x^2+2x-8 x34x2+2x8
color(magenta)(+x/2)(2x^2+4x-2)-> ul(x^3+2x^2-x) larr" Subtract"
" "0-6x^2+3x-8
color(magenta)(-3)(2x^2+4x-2)->" " ul(-6x^2-12x+6)larr" Subtract"
" "0color(magenta)(color(white)(.)+15x-14larr" Remainder")

color(magenta)(x/2-3+(15x-14)/(2x^2+4x-2))

May 17, 2017

(x^3 - 4x^2+2x - 8)/(2x^2+4x-2) = (x-6)/2 +(15x-4)/(2(x^2+4x-2))

Explanation:

When working with algebraic fractions, try to factorise first:

(x^3 - 4x^2+2x - 8)/(2x^2+4x-2)" "(larr "try grouping")/(larr"HCF, quadratic trinomial")

=(x^2(x-4)+2(x-4))/(2(x^2+2x+1))

= ((x-4)(x^2+2))/(2(x+1)(x+1))

This cannot be simplified, there are no common factors to cancel

Let's do long division:

(x^3 - 4x^2+2x - 8)/(2x^2+4x-2) = (x^3 - 4x^2+2x - 8)/(2(x^2+2x-1)

Let's divide by (x^2+2x-1) to start, and divide by 2 later

color(white)(......................................)x-6
x^2+2x-1 )bar(x^3 - 4x^2+2x - 8)
color(white)(.....................)ul(x^3 +2x^2-x)" "larr subtract
color(white)(........................)-6x^2+3x-8
color(white)(.........................)ul(-6x^2-12x-6)" "larr subtract
color(white)(.......................................)15x-14" "larr remainder

We still need to divide by 2. Therefore we have:

(x^3 - 4x^2+2x - 8)/(2x^2+4x-2) = (x-6)/2 +(15x-4)/(2(x^2+4x-2))