Page 31 - 新思维数学活动用书9 样章

2 Expressions and formulae

12 This is part of Brad’s classwork.

Question

Simplify 20x + 4
8
Answer
20x + 4 4(5x + 1) = 4 (5x + 1) 5x + 1
1
=
=
8 8 8 2 2

Use Brad’s method to simplify these fractions. Tip

a 6x + 9 b 20x + 30
6 50 Remember to
−
c 4x − 6 d 30 42x take out the
8 12 highest common
13 You already know that you add and subtract fractions by using a factor when you
common denominator. factorise the
×
+
×+
2
4
For example: += 43 25 = 12 10 = 22 numerator of
×
5 3 53 15 15
You can use the same method with algebraic fractions. each fraction.
1
×
+
1
For example: += 1 b×+ 1 a = ba
a b ab ab
Use the method shown to add and subtract these fractions.
a 1 + 1 b 1 + 1 c 1 − 1
x y c d x y
d 2 + 1 e 5 − 2 f 3 − 4
a b m n g h