SIMULTANEOUS EQUATIONS 1

Solve the following equations by substitution method.

x + y = 5

x + 3y = 3

Solution

x + y = 5 ----------- (i)

x + 3y = 3 ---------- (ii) 

 

from equation (i)

x + y = 5

x = 5 - y ----------(iii)

substitute equation (iii) in (ii) above,

x + 3y = 3

(5 - y)  + 3y = 3 

5 + 2y = 3            [since –y+3y=2y]

2y = 3 - 5

2y = -2

2       2

y = -1

From equation (iii)

x = 5 - y ----------(iii)

x = 5 - (-1)     [ since y = -1]

x = 6

Hence x=6 and y=-1.

TRY THIS………………………..

Solve the following equations by substitution method.

5x - 2y = 13

x  -  y = 2