How do you divide (-3x^3-3x^2-4x+1)/(3x-4) 3x33x24x+13x4?

1 Answer
Oct 15, 2017

I prefer long division.

Explanation:

(-3x^3-3x^2-4x+1)/(3x-4)3x33x24x+13x4

In long division form:

color(white)( (3x-4)/color(black)(3x-4)) color(white)( (-3x^3-3x^2-4x+1))/(") "-3x^3-3x^2-4x+1)3x43x4(3x33x24x+1)) 3x33x24x+1

Write -x^2x2 in the quotient:

color(white)( (3x-4)/color(black)(3x-4)) (color(white)("....")-x^2color(white)(-3x^2-4x+1))/(") "-3x^3-3x^2-4x+1)3x43x4....x23x24x+1) 3x33x24x+1

Multiply -x^2(3x-4) = -3x^2+ 4x^2x2(3x4)=3x2+4x2 and subtract from the dividend:

color(white)( (3x-4)/color(black)(3x-4)) (color(white)("....")-x^2color(white)(-3x^2-4x+1))/(") "-3x^3-3x^2-4x+1)3x43x4....x23x24x+1) 3x33x24x+1
color(white)(".....................")ul(3x^2- 4x^2)
color(white)(".................... .")-7x^2-4x

Write -7/3x in the quotient:

color(white)( (3x-4)/color(black)(3x-4)) (color(white)("....")-x^2-7/3xcolor(white)(-4x+1))/(") "-3x^3-3x^2-4x+1)
color(white)(".....................")ul(3x^2- 4x^2)
color(white)(".................... .")-7x^2-4x

Multiply -7/3x(3x-4) = -7x^2+ 28/3x and subtract from the dividend:

color(white)( (3x-4)/color(black)(3x-4)) (color(white)("....")-x^2-7/3xcolor(white)(-4x+1))/(") "-3x^3-3x^2-4x+1)
color(white)(".....................")ul(3x^2- 4x^2)
color(white)(".................... .")-7x^2-4x
color(white)("....................... .")ul(7x^2-28/3x)
color(white)("............................... .")-40/3x+ 1

Write -40/9 in the quotient:

color(white)( (3x-4)/color(black)(3x-4)) (color(white)("...")-x^2-7/3x-40/9color(white)(1))/(") "-3x^3-3x^2-4x+1)
color(white)(".....................")ul(3x^2- 4x^2)
color(white)(".................... .")-7x^2-4x
color(white)("....................... .")ul(7x^2-28/3x)
color(white)("............................... .")-40/3x+ 1

Multiply -40/9(3x-4) = -40/9x+ 160/9 and subtract from the dividend:

color(white)( (3x-4)/color(black)(3x-4)) (color(white)("...")-x^2-7/3x-40/9color(white)(1))/(") "-3x^3-3x^2-4x+1)
color(white)(".....................")ul(3x^2- 4x^2)
color(white)(".................... .")-7x^2-4x
color(white)("....................... .")ul(7x^2-28/3x)
color(white)("............................... .")-40/3x+ 1
color(white)("............................... .")ul(40/9x - 160/9)
color(white)("........................................... .")-151/9

The quotient is -x^2-7/3x-40/9 with a remainder of -151/9