SIMULTANEOUS EQUATIONS 2

Solve the following equations by substitution method.

x + y = 9

x + 3y = 13

Solution

x + y = 9 ----------- (i)

x + 3y = 13 ---------- (ii)

from equation (i)

x + y = 9

x = 9- y ----------(iii)

substitute equation (iii) in (ii) above,

x + 3y = 13

(9- y)  + 3y = 13

9+2y = 13

2y = 13 - 9

2y = 4

2      2

y = 2

From equation (iii)

x = 9- 2 ----------(iii)

x = 9- 2

 x = 7

Hence x=7 and y=2.

TRY THIS………………………..

4x - y = 20

3x + 2y = 70