Page 16 - 新思维数学活动用书8 样章

2.1 Constructing expressions

Challenge

10 Write an expression for the perimeter and an expression for the area of each rectangle.
Simplify each expression.
a b
8w cm 5 y cm
8

v + 3 cm 9x cm
11 The longest side of a triangle is a cm. Tip
The second side is b cm shorter than the first side.
The third side is half as long as the second side. Start by writing

Write an expression, in its simplest form, for the perimeter of expressions for
the triangle. the second and
12 The price of one kilogram of lemons is $l. third sides.
The price of one kilogram of potatoes is $p.

The price of one kilogram of rice is $r. Tip
Write an expression for the total cost of What fraction of
a 1 kilogram of potatoes, 3 kilograms of lemons and 2 kilograms 1 kg is 200 g?

of rice
b 3 kilograms of potatoes and one-quarter of a kilogram of rice
c 200 grams of rice
d 600 grams of rice and 750 grams of lemons.

13 Sion thinks of a number, y.
Choose the correct expression from the cloud for when Sion
a adds 3 to one-quarter of y, then multiplies by 8 4    y + 8    8    3y + 4   
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b adds 8 to one-third of y, then multiplies by 4  3y   y 4 

c adds 4 to three-quarters of y, then multiplies by 8 4   8 + 3   8   4 + 3  
d adds 3 to three-eighths of y, then multiplies by 4.

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