One Problem at a Time

Dividing Polynomial Using Long Division

Problem 258: Let’s divide 2x^3 - 11x^2 - 41x + 9 by x - 8.

Solution: Write the problem as a long division problem.

    \[x-8 \overline{)2x^3 - 11x^2 - 41x + 9}\]

When doing long division, we make sure that the dividend is in descending order of degree. In this case, it is.

We start the long division by dividing 2x^3 (the first term in the dividend) by x (the first term in the divisor). Then we repeat the process.

    \[\begin{matrix}2x^2 + 5x - 1 \\ \qquad x-8 \overline{)2x^3 - 11x^2 - 41x + 9} \\ \underline{-(2x^3 - 16x^2)} \\ \qquad \qquad \qquad \qquad 5x^2 - 41x + 9 \\ \qquad \qquad \qquad \underline{-(5x^2 - 40x)} \\ \qquad \qquad \qquad \qquad \qquad \quad -x + 9 \\ \qquad \qquad \qquad \qquad \qquad \quad \underline{-(-x+8)} \\ \qquad \qquad \qquad \qquad \qquad \qquad \qquad 1 \end{matrix}\]

The result is given by the quotient and the remainder over the divisor. That is,

    \[2x^2 + 5x -1 + \frac{1}{x-8}.\]

Leave a Reply

Your email address will not be published. Required fields are marked *