Page 36 - 新思维数学学生用书7 样章

2.1 Constructing expressions

7 a Zara is classifying some expression cards
The expression
into groups of equivalent expressions. 5n + 4 is the same as
Explain why Zara is correct. 5 × n + 4 and 4 +
b Classify these cards into groups of 5 × n.
equivalent expressions.

A 2n + 3 B 2 × n − 3 C 3 × n + 2 D 2 × n + 3

E 3 − 2n F 3 – 2 × n G 3 + 2n H 2 + 3n

I 2n − 3 J 3n + 2 K 3 + 2 × n L 2 + 3 × n

8 This is part of Pedro’s classwork.

Question
In a clothes shop, T-shirts cost $t and shirts cost $s.
Write an expression for the total cost of:

a one T-shirt and one shirt b four T-shirts and two shirts
Answers
a t × s b 2t + 4s

Explain the mistakes that Pedro has made and write down the

correct answers.
9 Write an expression for each of these situations. You can choose
your own letters, but make sure that you explain what your letters Tips
represent. In question
a the total cost of two tacos and four burritos 9 part a, you
b the total cost of eight lemon cakes and five carrot cakes could start by

c the total value of six gold coins is doubled explaining ‘Let
d the total value of five silver coins is tripled the cost of one

10 Write an expression for each of these. taco be $t and
a x more than y the cost of one
b x less than y burrito be $b.
c m more than two times n ‘Doubled’
d a less than three times b means × 2.
e p multiplied by q ‘Tripled’

f four times g multiplied by h means × 3.

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