SIMULTANEOUS EQUATIONS A3

Solve the following equations by substitution method.

6x + y = 15

x +  3y = 11

solution

6x  + y = 15----------- (i)

x + 3y = 11---------- (ii)

from equation (i)

6x + y = 15

y = 15 - 6x ----------(iii)

Substitute equation (iii) in (ii) above,

x + 3(15 - 6x) = 11

x + 45 - 18x = 11

x - 18x = 11- 45

-17x  = -34

-17x  = -34

-17       -17

x = 2

From equation (iii)

y = 15 - 6x ----------(iii)

y = 15 – 6(2)

y = 15 – 12

y = 3

Hence x=2 and y=3.