Polynomial functionsOptional method

Synthetic division - by a linear divisor

Divide a polynomial by using its coefficients, then identify the quotient and remainder.

Optional method: synthetic division is not required by the AP Precalculus exam. Polynomial long division covers the required division skill.

  • Write the coefficients in descending powers, including a for every missing power.
  • Use the zero of the divisor: for , or for .
  • Bring down the first coefficient. Multiply it by , write the product under the next coefficient, and add. Repeat across the row.
  • The last number is the remainder . The preceding numbers are the quotient coefficients, starting one degree lower.

Example 1

An exact division

Divide by .

Use . Bring down the first coefficient, then multiply and add.
Synthetic division: coefficients, products, then sums.
Use root
Multiply by the rootBring down
Add down each column
Quotient coefficientsRemainder
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd

Read the quotient one degree lower. The last number is the remainder.

Quotient Remainder

The quotient has degree . A zero remainder means is a factor.

Example 2

Reorder first and include a missing power

Divide by .

Write descending powers and insert for the missing linear term.

Use . Bring down the first coefficient, then multiply and add.
Synthetic division: coefficients, products, then sums.
Use root
Multiply by the rootBring down
Add down each column
Quotient coefficientsRemainder
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd

Read the quotient one degree lower. The last number is the remainder.

Quotient Remainder

The quotient has degree . The remainder is , so is not a factor of .

Remember
Check with . To write the division as a fraction, use , where . This table is for a linear divisor with leading coefficient .

Your turn

Question 1

Use synthetic division. State the quotient and remainder.

Check answer
Use . Bring down the first coefficient, then multiply and add.
Synthetic division: coefficients, products, then sums.
Use root
Multiply by the rootBring down
Add down each column
Quotient coefficientsRemainder
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd

Read the quotient one degree lower. The last number is the remainder.

Quotient Remainder
Question 2

Use synthetic division. State the quotient and remainder.

Check answer
Use . Bring down the first coefficient, then multiply and add.
Synthetic division: coefficients, products, then sums.
Use root
Multiply by the rootBring down
Add down each column
Quotient coefficientsRemainder
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd

Read the quotient one degree lower. The last number is the remainder.

Quotient Remainder
Question 3

Use synthetic division. State the quotient and remainder.

Check answer
Use . Bring down the first coefficient, then multiply and add.
Synthetic division: coefficients, products, then sums.
Use root
Multiply by the rootBring down
Add down each column
Quotient coefficientsRemainder
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd

Read the quotient one degree lower. The last number is the remainder.

Quotient Remainder
Question 4

Use synthetic division. State the quotient and remainder.

Check answer
Use . Bring down the first coefficient, then multiply and add.
Synthetic division: coefficients, products, then sums.
Use root
Multiply by the rootBring down
Add down each column
Quotient coefficientsRemainder
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd

Read the quotient one degree lower. The last number is the remainder.

Quotient Remainder
Question 5

Use synthetic division. State the quotient and remainder.

Check answer
Use . Bring down the first coefficient, then multiply and add.
Synthetic division: coefficients, products, then sums.
Use root
Multiply by the rootBring down
Add down each column
Quotient coefficientsRemainder
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd
MultiplyAdd

Read the quotient one degree lower. The last number is the remainder.

Quotient Remainder