Page 45 - 新思维数学学生用书9 样章

2 Expressions and formulae

6 a Simplify these expressions. Tip

i a + b ii 5a + 3b iii 2a + 3
5 5 12 4 15 5 a 3
iv a + 3 v 3a + 4 vi 4a + 3 iv 4 + b
4 b 10 b 9 2b a × b 3 × 4
b For each expression in part a, choose values for a and b. = 4 × b + b × 4 = ...
Substitute your values into the questions and work out the

numerical answers.
Substitute your values into your algebraic answer and work
out the numerical answers.
Check your numerical answers match, to show your algebraic

expressions are correct.

Activity 2.5

Work with a partner for this activity.
Here are eight fractions cards labelled A to H.

A 3x B 4y C 7z D m
5 3 8 8

E 7k F 4p G 1 H 5h
12 9 2 4
Take it in turns to ask your partner to add or subtract two of the cards.
For example, you could say ‘C + F’ or ‘H – B’. You can choose.
Work out the answer yourself and mark your partner’s work.

Discuss any mistakes that have been made. Do this twice each.

Think like a mathematician

7 Work with a partner to answer this question.
This is part of Iain’s homework.

Question
6x + 2
Simplify 2

Answer
6x + 2 2(3x + 1) 2 (3x + 1)
1
2 = 2 = 2 1 = 3x + 1

44