Page 51 - Maths Skills - 7

Simple Equations 49

Solution: (i) 6z + 10 = – 2 3l 2
(ii) = 3
or 6z = – 2 – 10 2 2
or 3l = × 2
3
6z = – 12 2 × 2 1 4
3
or z = – 12 = – 2 or l = 3 × = 9
6
1
(iii) 2b – 5 = 3 (iv) 2y – = 1
3 2 3
1
2b = 3 + 5 = 8 2y = + 1
3 3 2
2b = 8 × 3 2y = 2 + 3 = 5
6 6
3 5 5
b = 8 × y = =
2 6 × 2 12
b = 4 × 3 = 12

Example 3: Solve the following equations and check your answer also.
(i) 3(n – 5) = 21 (ii) 3 –2 (2 – y) = 7

Solution: (i) 3(n – 5) = 21

On transposing 3 to other side Verification: 3(n – 5) = 21

n – 5 = 21 or 3 (12 – 5) = 21
3
or n – 5 = 7 or 3 (7) = 21
or n = 7 + 5 or 21 = 21

or n = 12 \ LHS = RHS

(ii) 3 – 2 (2 – y) = 7

– 2(2 – y) = 7 – 3 Verification: 3 – 2 (2 – 4) = 7
or – 2(2 – y) = 4 or 3 – 2 (–2) = 7
4 or 3 + 4 = 7
2 – y = – 2 or 7 = 7
or 2 – y = – 2 \ LHS = RHS

On transposing 2 to other side, we get
– y = – 4

On dividing both the sides by – 1, we get y = 4

Exercise 3.3

1. Solve the following by method of transposition and verify your answers by substituting in the equations:

(i) 3s + 12 = 0 (ii) 3q – 5 = 7 (iii) 8m – 3 = 13
5
(iv) x = – 5 (v) 17 + 3s = – 4 (vi) 0 = 16 + 4 (m – 6)
2