How do you divide (x^4-2x^3+2x^2-3x+3)/(x^2-3) x42x3+2x23x+3x23?

1 Answer
May 18, 2017

Given: (x^4-2x^3+2x^2-3x+3)/(x^2-3)x42x3+2x23x+3x23

Write the divisor with a 0 coefficient for missing term

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))color(white)((x^4-2x^3+2x^2-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)x2+0x3x2+0x3(x42x3+2x23x+3)xx42x3+2x23x+3

To determine the first term in the quotient divide the first term in the dividend by the first term in the divisor x^4/x^2=x^2x4x2=x2 write x^2x2 in the quotient:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2color(white)(2x^3+2x^2-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)x2+0x3x2+0x3x22x3+2x23x+3xx42x3+2x23x+3

Multiply the term in the quotient by the divisor:

x^2(x^2+0x-3) =x^4+0x^3-3x^2x2(x2+0x3)=x4+0x33x2

Make it negative:

-x^4-0x^3+3x^2x40x3+3x2

Write it below the dividend:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2color(white)(2x^3+2x^2-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)x2+0x3x2+0x3x22x3+2x23x+3xx42x3+2x23x+3
color(white)(....................)ul(-x^4-0x^3+3x^2)

Perform the addition and bring down the x term:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2color(white)(2x^3+2x^2-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)
color(white)(....................)ul(-x^4-0x^3+3x^2)
color(white)(..........................)-2x^3+5x^2-3x

To find the next term in the quotient, divide the first term in the sum by the first term of the divisor:

(-2x^3)/x^2=-2x

Write it as the next term of the quotient:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2-2xcolor(white)(2x^2-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)
color(white)(....................)ul(-x^4-0x^3+3x^2)
color(white)(..........................)-2x^3+5x^2-3x

Multiply the term in the quotient by the divisor:

-2x(x^2+0x-3) =-2x^3+0x^2+6x

Make it negative:

2x^3+0x^2-6x

Write it below the sum:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2-2xcolor(white)(2x^2-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)
color(white)(....................)ul(-x^4-0x^3+3x^2)
color(white)(..........................)-2x^3+5x^2-3x
color(white)(...............................)ul(2x^3+0x^2-6x)

Perform the additions and bring down the constant term:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2-2xcolor(white)(2x^2-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)
color(white)(....................)ul(-x^4-0x^3+3x^2)
color(white)(..........................)-2x^3+5x^2-3x
color(white)(...............................)ul(2x^3+0x^2-6x)
color(white)(..........................................)5x^2-9x+3

To find the next term in the quotient, divide the first term in the sum by the first term of the divisor:

(5x^2)/x^2=5

Write it as the next term of the quotient:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2-2x+5color(white)(-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)
color(white)(....................)ul(-x^4-0x^3+3x^2)
color(white)(..........................)-2x^3+5x^2-3x
color(white)(...............................)ul(2x^3+0x^2-6x)
color(white)(..........................................)5x^2-9x+3

Multiply the term in the quotient by the divisor:

5(x^2+0x-3)=5x^2+0x-15

Make it negative:

-5x^2+0x+15

Write it below the sum:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2-2x+5color(white)(-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)
color(white)(....................)ul(-x^4-0x^3+3x^2)
color(white)(..........................)-2x^3+5x^2-3x
color(white)(...............................)ul(2x^3+0x^2-6x)
color(white)(..........................................)5x^2-9x+3
color(white)(.......................................)ul(-5x^2+0x+15)

Perform the addition:

color(white)( (x^2+0x-3)/color(black)(x^2+0x-3))(x^2-2x+5color(white)(-3x+3))/(| color(white)(x)x^4-2x^3+2x^2-3x+3)
color(white)(....................)ul(-x^4-0x^3+3x^2)
color(white)(..........................)-2x^3+5x^2-3x
color(white)(...............................)ul(2x^3+0x^2-6x)
color(white)(..........................................)5x^2-9x+3
color(white)(.......................................)ul(-5x^2+0x+15)
color(white)(...............................................)-9x+18

Because -9x+18 is of order 1 and the divisor is of order 2, we stop and declare -9x+18 to be the remainder.