Page 46 - 新思维数学学生用书7 样章

2.3 Collecting like terms

11 Marcus is trying to complete this algebraic pyramid. I don’t think there
is enough information
12c +11d to be able to fill in all
the blocks.
7c +3d

2c +6d

c + d

Is Marcus correct? Explain your answer.
Copy the pyramid and fill in as many blocks as you can.
12 This is the method Giovanna uses to simplify the expression 3a + 5a .
4 12

3a 5a
To work out + , I need to use a common
4 12
denominator of 12.

3a = 3 × 3a = 9a , so 9a + 5a = 14a .
4 3 × 4 12 12 12 12
14a 7a
I can now write in its simplest form as .
12 6

a Critique Giovanna’s method. Is it easy to follow?
Do you think this is the best method to use to answer this type

of question or can you improve the method? Discuss your
answers with a partner. Tip
b Simplify these expressions. Write your answers in their
simplest form. An improper

i a + 5 a ii y _ y iii 2x _ 5x fraction is a
2 8 2 6 3 12 fraction where
13 Simplify these expressions. the numerator is
Write your answers in their simplest form and as an improper fraction. larger than the

a 3a + a b 3b + 7b c 2c + c denominator.
4 2 5 15 3

Summary checklist

I can collect like terms.

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