Exercise (1- 7)
1
State the property of the multiplication of rational numbers used in each of the following statements: [a] – 1 × 2 = 2 × ( – 1 )
[d] 5 × 1 = 5
[b] – 3 × ( – 7 ) = 1
[e] 0.8 × 0 = 0
2
3
3
7
2
4
3
4
[c] – 7 × ( 5 × 4 ) = ( 5 × 4 ) ( – 7 ) 20
2
2
2
20
Complete: [a] 2 × (– 4 ) = – 4 × ....
[d] – 4 × .... = 1
[b] 2 ( 2 + 1 ) = 2 × 2 + ....
[e] The rational number which has no multiplicative inverse is ...
3
5
3
5
2
3
[c] 2 × 3 = .... 3
11
2
Mental Math
3
Find the value of n in each of the following: [a] 5 × n = 5
7 7 [b] – 7 × n = 0 3 [ c ] n [ 1 + ( – 3 ) ] = n × 1 + 5 × ( – 3 ) 2 5 2 5
4
[ d ] n × 17 = 1 3
[ e ] – 7 × ( – 3 ) = n 3
7
Use the properties of distribution of multiplication over addition of rational numbers to calculate each value:
[a] 4 × 11 + 4 × 16
[ c ] – 3 × 8 + 5 × (– 3 ) + (– 3 )
[b] 5 × 3 + 5 × 9
[ d ] 18 × 25 + (– 3 ) × 25
9
9
12
20
12
Mathematics For First form preparatory
7
5
7
9
7
7
9