Page 24 - 新思维数学学生用书9 样章

2.1 Substituting into expressions

a Look at Pierre’s answers. Do you think his working and answers are correct?

Give a reason for your answer.
b Discuss your answers to part a with other learners in your class.
Do you agree or disagree with the other learners?
If you made a mistake, do you understand the mistake you made?
If other learners made a mistake, explain to them the mistake they made.

Think like a mathematician

5 Work with a partner to answer this question.

The expression x + y has a value of 15.
2
Write down three pairs of integer values for x and y when
a x and y are both positive numbers
b x and y are both negative numbers

c x is negative and y is positive, or vice versa.
Discuss the methods you used, and the values you found, with other learners
in your class.

6 Copy and complete the workings to find the value of each expression when m = 2 and p = −4.

a 4(m + 2 ) = 42 2+× − 4) b p − 3 mp = − 4 − 32×× − 4
3
3
(
)
(
p
= 42 − ( ) = +
=× =
4
=
p 
c    m  5 + p () = ( ) 5 +−4 3
( )
−4
3
2
5
= ( ) −
= −
=

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