Long Division of Polynomials

Long Division of Polynomials

TGM Original Questions

\(\mathrm{P}(x)=\mathrm{D}(x)\mathrm{Q}(x)+\mathrm{R}(x)\)

\(\mathrm{D}\) is a nonzero polynomial. The remainder is zero or has degree less than \(\mathrm{D}\).

\(\dfrac{\mathrm{P}(x)}{\mathrm{D}(x)}=\mathrm{Q}(x)+\dfrac{\mathrm{R}(x)}{\mathrm{D}(x)}\qquad \mathrm{D}(x)\ne0\)

Arrange terms in descending powers, inserting zero coefficients for missing powers. Divide the leading terms, multiply, subtract and repeat.

Example: divide \(3x^3-4x^2+5x+4\) by \(x^2-3x\)

Quotient termSubtractRemainder
\(3x\)\(3x(x^2-3x)\)\(5x^2+5x+4\)
\(5\)\(5(x^2-3x)\)\(20x+4\)

Quotient: \(3x+5\). Remainder: \(20x+4\).

Check: \(3x^3-4x^2+5x+4=(x^2-3x)(3x+5)+(20x+4)\).

The remainder theorem finds only the remainder; use division when the quotient is also needed.

Need help? Join our A-Maths tuition classes.

Learn more