How do you divide (4x^3+2x-6) /(x-1)4x3+2x6x1?

1 Answer
Oct 30, 2015

See explanation
Bit long, but the process takes quite a bit of getting used to!

Explanation:

You asked how to do it so I am explaining the process:

You divide the sequential xx parts in the numerator into sequential xx parts of the denominator. Each stage leaves a remainder for which the process is repeated.

Demonstration within the context of this question.

color(green)("==============================")==============================
Step 1: 4x^3 divide x = 4x^24x3÷x=4x2

Used the 4x^34x3 from 4x^3+2x-64x3+2x6 and the xx from x-1x1

So the color(red)("first")first part of your answer is color(blue)(4x^2)4x2

color(green)("============================")============================
Step 2: Find the remainder

4x^2 times (x-1) = 4x^3 - 4x4x2×(x1)=4x34x
This is then subtracted so we have:

4x^3 + 2x -64x3+2x6 .......Original equation
(4x^3 -4x) -(4x34x) ...... Subtract
~~~~~~~~~~~~~
color(white)("xxxxxx") 6x - 6xxxxxx6x6. This is the first remainder

color(green)("=================================")=================================

Step 3.

Again divide the 6x6x in the previous remainder by the xx in x-1x1 giving 66.

So the color(red)("second")" "second part of the answer is color(blue)(+6)+6

6(x-1) =6x-66(x1)=6x6 which is subtracted from the most recent remainder giving:

4x^3 + 2x -64x3+2x6 .......Original equation
(4x^3 -4x) -(4x34x) ...... Subtract
~~~~~~~~~~~~~
color(white)("xxxxxx") 6x - 6xxxxxx6x6. This is the remainder
color(white)("xxxxxx") ( 6x - 6) -xxxxxx(6x6). Subtract
~~~~~~~~~~~~~~~~~~~~~~~~~~
color(white)("xxxxxxx") 0 + 0" "xxxxxxx0+0 which is the second remainder.

The zeros mean that we have an exact division

In this case
(4x^3 +2x-6)/(x-1) =4x^2+64x3+2x6x1=4x2+6

Suppose we had ended up with a remainder that the x " in " (x-1)x in (x1) could not be divided into. In that case we would express the whole of that remainder as a fraction with (x-1)(x1) as the denominator.

Suppose that had ended up with a remainder of just 2. Then in that case the answer would be:

4x^2 + 2/(x-1) + 64x2+2x1+6

Hope this helps. It takes a lot of practice.