SIMULTANEOUS EQUATIONS 1

Solve the following equations by substitution method.

2x - y = 1

x + y = 8

Solution

2x - y = 1----------- (i)

x + y = 8---------- (ii)

from equation (ii)

x + y = 8

x = 8- y ----------(iii)

substitute equation (iii) in (i) above,

2x - y = 1

2(8- y) - y = 1

16 - 2y - y = 1  

16 - 3y = 1 (since -2y – y = -3y)

16- 1 = 3y  [after collecting like terms]

15 = 3y

15 = 3y

 3     3

5 = y

From equation (iii)

x = 8- y ----------(iii)

x = 8- 5

 x = 3

Hence x=3 and y=5.

TRY THIS…………………….

Solve the following equations by substitution method.

2x - 3y = 4

x + y = 7