Page 25 - 新思维数学活动用书9 样章

2 Expressions and formulae

2.4 Expanding the product of two linear

expressions

Exercise 2.4 Key words

brackets
Focus expand

1 Copy and complete these multiplications, using the multiplication grid.
a 23 × 34 b 18 × 42

× 20 3 × 10 8
30 600 90 40 400
4 80 12 2

Answer: 600 + 90 + 80 + 12 = Answer: 400 + + + =

2 Use the same method as in Question 1 to expand these brackets.
The first one has been done for you.
a (x + 2)(x + 3) b (x + 1)(x + 4)

× x +2 × x +1
x x 2 +2x x x 2
+3 +3x +6 +4

Answer: x + 2x + 3x + 6 = Answer: x + + + =
2
2
x + 5x + 6 x + +
2
2
c (x + 5)(x + 6) d (x + 3)(x + 9)
× x +5 × x +3

x x 2 x
+6 +9

Answer: x + + + = Answer: x + + + =
2
2
2
x + + x + +
2

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