Page 23 - 新思维数学活动用书8 样章

2 Expressions, formulae and equations

9 Expand each expression. Three of them have been started for you.
a a(a + 1) = a × a + a × 1 = a +
2
b b(b − 5) c c(3c + 6) d e(4e + 9)

e i(3i + 7x) = i × 3i + i × 7x = 3i +
2
f j(3a − 7j) g k(3k − 6x) h 3m(m + 3x)

i 3r(3r − x − 3) = 3r × 3r − 3r × x − 3r × 3 = 9r − −
2
j 2a(3 + 2a + b) k 3x(−z − y − x)
10 Here are some expression cards.
Sort the cards into groups of equivalent expressions.

A 8y(5 + 6y) B 4y(5y + 6y )
2

C 2y(24y + 20) D 2y (10 + 12y)
2

E 4(10y + 12y ) F 4y (6y + 5)
2
2
G y (20 + 24y) H y(40 + 48y)
2

Challenge
11 Write down and then simplify an expression for the area of each rectangle.

a (2x + 1) cm b (3y − 2) cm
4 cm
2y cm

12 Expand and simplify each expression.

a a(a + 3) + a(a + 4) b b(b + 3) + b(4b + 5)
c c(3c + 4) + c(5c + 6) d d(3d + 4) − d(d + 5)
e e(3 + 4e) − e(5e − 6) f f(3f + 4g) − 5f(6f − 7g)

22
22