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The Guides for Effective Instruction in Mathematics Revised

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C2.1 Add and subtract monomials with a degree of 1 that involve whole numbers, using tools.

Activity 1: Addition and Subtraction of Monomials

Add or subtract the 2 terms below comprising monomials with a degree of 1:

a) \(5m + 12m\)

Strategy

I can add up the 2 terms, because they have the same variables.

Number line with values of zero to 20 and value 17 is circled. Two arrows pointing left from value zero to 5 and 5 to 12. 5 “m”, plus, 12 “m”, minus, 17 “m”.

b) \(34c - 13c\)

Strategy

I can subtract the 2 terms, because they have the same variables.

Number line with values zero to 35, and value 21 is circled. One arrow pointing right from value zero to 34 and one arrow pointing left from 35 to 21. Equation: 34 “c”, minus, 13 “c“, equals 21 “c”

c) \(14ab + 8m\)

Strategy

I can't add these 2 terms together, because they don't have the same variables. The answer remains the same as the equation.

Number line with values zero until 15 and value 8 is circled. A red arrow is pointing right from value zero until 8. A blue arrow is pointing right from value zero until 14. Equation: 14 “a” “b”, plus 8 “m”, equals, 14 “a” “b”, plus 8 “m”.

d) \(35c - 32a\)

Strategy

I can't subtract these 2 terms because they don't have the same variables. The answer remains the same as the equation.

Number line with values of minus 35 until 35. Values minus 32 and 35 are circled. A blue arrow is pointing left from value zero until minus 32 and a red arrow pointing right from value zero until value 35. Equation: 35 “c”, minus 32 “a”, equals, 35 “c”, minus 32 “a”.

Source : En avant, les maths!, 7e année, CM, Algèbre, p. 3-4.

Activity 2: Addition and Subtraction of Monomials

Add and subtract the following monomials:

  • \(3a-5a+6a+4a\)
  • \(4c+6c+5b-3c\)
  • \(2d+7+5e+3-2e+4d\)