Skill: Subtract polynomials

Explanation and Free Practice Resources

Subtracting polynomials is understood as adding the additive inverse of the subtrahend: every term in the polynomial being subtracted changes sign, and only like terms—those with identical variable parts and exponents—are combined by adding their coefficients. This includes simplifying one-variable polynomials with integer or rational coefficients and whole-number exponents, supporting later work with equations and functions; polynomial division, multivariable generalizations, and abstract polynomial theory are outside this scope.

Detailed Explanation: Subtract polynomials

To subtract polynomials, change the sign of every term in the polynomial being subtracted. Then combine like terms.

Example:

(3x2−5x+7)−(x2+2x−4)(3x^2-5x+7)-(x^2+2x-4)

Step 1: Change the signs in the second polynomial.

The subtraction sign applies to every term:

3x2−5x+7−x2−2x+43x^2-5x+7-x^2-2x+4

Step 2: Group like terms.

Like terms have the same variable and exponent:

(3x2−x2)+(−5x−2x)+(7+4)(3x^2-x^2)+(-5x-2x)+(7+4)

Step 3: Combine the coefficients.

2x2−7x+112x^2-7x+11

Therefore,

(3x2−5x+7)−(x2+2x−4)=2x2−7x+11\boxed{(3x^2-5x+7)-(x^2+2x-4)=2x^2-7x+11}

Remember: only combine like terms, such as x2x^2 with x2x^2 and xx with xx.

Learn by doing: Subtract polynomials

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Like Terms - Combine - Order 2 - Whole - One Variable - Expression to Pair


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