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Dividing a Polynomial by a Binomial

To divide a polynomial by a binomial, use a procedure called polynomial long division, which closely mirrors the long division algorithm for whole numbers. Just as dividing 875 by 25 involves repeatedly dividing, multiplying, and subtracting digit groups, dividing a polynomial by a binomial involves the same cycle applied to polynomial terms.

The general procedure is:

  1. Set up the problem. Write the dividend (the polynomial being divided) under the long division bracket and the divisor (the binomial) outside. Make sure the dividend is in standard form — terms arranged in descending order of degree with no missing powers.
  2. Divide the leading term of the current dividend by the leading term of the divisor. Write the result in the quotient, positioned above the term of the dividend that matches its degree.
  3. Multiply the entire divisor by the term just written in the quotient. Align the resulting product under the corresponding terms of the dividend.
  4. Subtract. Change the signs of the product obtained in Step 3 and add (this is equivalent to subtracting). Then bring down the next term from the dividend.
  5. Repeat Steps 2–4 using the new expression obtained after subtraction and bringing down. Continue until the degree of the remaining expression is less than the degree of the divisor.
  6. Handle the remainder. If the remainder is zero, the division is exact. If a nonzero remainder results, express it as a fraction with the remainder in the numerator and the divisor in the denominator, and append it to the quotient.

To verify the result, multiply the quotient by the divisor — the product should equal the original dividend. When the divisor involves subtraction (for example, x3x - 3), take extra care during the subtraction steps: it may be safer to change all signs and then add rather than subtracting directly, to avoid sign errors.

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Updated 2026-04-21

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Ch.6 Polynomials - Elementary Algebra @ OpenStax

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