Page 49 - 新思维数学学生用书8 样章
P. 49
2 Expressions, formulae and equations
11 Read what Zara says.
When I expand
5(2x + 6) + 2(3x − 5), then
collect like terms and finally
factorise the result, I get
the expression
4(4x + 5).
Show that she is right.
12 Read what Marcus says.
When I expand
6(3y + 2) − 4(y − 2), then
collect like terms and
finally factorise the result,
I get the expression
2(7y + 2).
Show that he is wrong. Tip
Explain the mistake Marcus has made.
13 The diagrams show two rectangles. You need to
factorise the
2a A 3d B expressions to
find the lengths
length length of A and B.
The area of rectangle A is 2a + 18a. You will need an
2
The perimeter of rectangle B is 14d − 10c. extra step first
Write an expression for the length of each rectangle, for rectangle B.
in its simplest form.
Work with a partner.
Take it in turns to define the following terms.
a What is a factor?
b What is the highest common factor?
c What is factorising?
How did your answers to a and b help with your answer to c?
Summary checklist
I can use the highest common factor (HCF) to factorise an expression.
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