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Grade 9 · Math · Unit 3 of 8

Polynomials

Add, subtract, expand and evaluate

What your child practises

Naming polynomials by terms and degree, combining like terms, subtracting polynomials, multiplying and dividing by a constant, and substituting values for x.

NWT Curriculum learning standard: Operations with polynomials of degree 2 or less: add, subtract, multiply and divide by a constant

How we explain it

Children can open this short lesson before they practise.

  1. Like terms have the same variable and exponent. Only combine those.
  2. To add polynomials, combine like terms.
  3. To expand, multiply each term inside the brackets: a(b + c) = ab + ac.

Example: (3x + 2) + (x − 5) = ? Combine the x terms: 3x + x = 4x. Combine the numbers: 2 − 5 = −3. Answer: 4x − 3

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Classify the polynomial 2x² + 9 by its number of terms.

    • quadrinomial
    • binomial
    • trinomial
    • monomial

  2. Question 2

    What is the degree of 7x − 3?

    answer box

  3. Question 3

    Add: (9x² + x + 7) + (9x² − 6x − 6)

    • 18x² − 5x − 3
    • 18x² − 4x + 1
    • 19x² − 5x + 1
    • 18x² − 5x + 1
    • 16x² − 5x + 1

  4. Question 4

    Subtract: (−9x² − x + 3) − (9x² − 9x − 3)

    • −18x² + 8x + 7
    • −18x² − 10x
    • −18x² + 8x − 7
    • −10x
    • −18x² + 8x + 6

  5. Question 5

    Expand: 5(x² − x − 4)

    • 6x² + 4x + 1
    • 5x² + 3x − 20
    • 5x² − 5x − 4
    • 5x² − x − 4
    • 5x² − 5x − 20

  6. Question 6

    Divide: (10x² + 6x + 6) ÷ 2

    • 5x² + 2x + 3
    • 5x² + 6x + 6
    • 5x² + 3x + 3
    • 10x² + 6x + 3
    • 5x² + 4x + 3

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