Page 17 - 新思维数学学生用书8 样章

1 Integers

8 These are multiplication pyramids.
a b c

–8

2 –4 –3 –3 5 –1 –4 –5 –2

Each number is the product of the two numbers below it. For example, in a, 2 × −4 = −8
Copy and complete the multiplication pyramids.

9 a Draw a multiplication pyramid like those in Question 8, with the integers −2, 3 and −5 in
the bottom row, in that order. Complete your pyramid.

If you change the order
of the bottom numbers,
the number at the top of
the pyramid is the same.

b Is Zara correct? Test her idea by changing the order of the

numbers in the bottom row of your pyramid.
10 Find the missing numbers in these multiplications.
a −3 × = −12 b −5 × = 45
c × −6 = 24 d × −10 = 80

Think like a mathematician Tip

11 A multiplication can be written as a division. A conjecture is
For example, 5 × 8 = 40 can be written as 40 ÷ 8 = 5 or a possible value

40 ÷ 5 = 8 based on what
a Here is a multiplication: −4 × 6 = −24 you know.
Write it as a division in two different ways.
b Write a multiplication of a positive integer and a

negative integer.
Then write it as a division in two different ways.
c Here is a multiplication: −7 × −2 = 14
Write it as a division in two different ways.

d Write a multiplication of two negative integers.
Then write it as a division in two different ways.

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