SIMULTANEOUS EQUATIONS 2

Solve the following equations by substitution method.

x + y = 10

x + 3y = 18

Solution

x + y = 10 ----------- (i)

x + 3y = 18 ---------- (ii)

from equation (i)

x + y = 10

x = 10 - y ----------(iii)

substitute equation (iii) in (ii) above,

x + 3y = 18

(10 - y)  + 3y = 18  

10+2y = 18            [since –y+3y=2y]

2y = 18 - 10

2y = 8

2      2

y = 4

From equation (iii)

x = 10 - 4 ----------(iii)

x = 6

Hence x=6 and y=4.

TRY THIS………………………..

5x - 2y = 17

x  -  y = 2