How do you divide (2x^3-11x^2+13x-44)div(x-5)(2x311x2+13x44)÷(x5) using synthetic division?

1 Answer
Mar 8, 2018

2x^2-1x+8 color(white)("xxx")(-4)/(x-5)2x21x+8xxx4x5

Explanation:

Note:
color(white)("XXX")color(magenta)5XXX5 (used below) is the value of xx required to make the divisor, (x-5)(x5) equal to zero.

rows [0] and [4] are not really part of synthetic division; I include them for reference purposes only.

row [1] are the coefficients of the powers of xx (when the expression is formed in standard notation and using 00 for any missing powers of xx).

row [2] contains, for each column, the product of color(magenta)55 (see above) and the value from the previous column of row [3].

row [3] contains, for each column, the sum of the values in the same column for rows [1] and [2]

The notations used in the (optional) row 4 are the powers of xx from the (optional) row [1] reduced by 1, with the final column, marked as color(gray)("R")R, the remainder.

{: ([0],," | ",color(gray)(x^3),color(white)("x")color(gray)(x^2),color(white)("x")color(gray)(x^1),color(white)("x")color(gray)(x^0)), ([1],," | ",2,-11,+13,-44), ([2],ul(+color(white)("xx"))," | ",ul(color(white)("xxxx")),ul(color(white)("x")10),ul(color(white)("x")-5),ul(color(white)("x")40)), ([3],xx color(magenta)5," | ",color(white)("x")2,color(white)("x")-1,color(white)("xxx")8,color(white)("x")-4), ([4],," | ",color(gray)(x^2),color(white)("x")color(gray)(x^1),color(white)("xx")color(gray)(x^0),color(white)("xx")color(gray)R) :}

Normally when performing synthetic division, only rows [1], [2], and [3] are required.