SOLVING SIMULTANEOUS LINEAR EQUATIONS 1

Example 1

The total age of Ali and Halim is 35 years.  Halim is 5 years older than Ali.  Find their ages.

Solution:

Let x = Ali's age

           y = Halim's age

      x + y = 35   ------------------------(1)

         y = x + 5   -----------------------(2)

Subtitute (2) into (1)

x + x + 5 = 35

    2x + 5 = 35

                2x = 35 - 5

           2x = 30

               x = 30/2

            x = 15

Subtitute x = 15 into (2)

      y = 15 + 5

y = 20

Therefor, Ali is 15 years old and Halim is 20 years old.

SIMULTANEOUS LINEAR EQUATIONS ( SUBSTITUTION METHOD)

Solve the following simultaneous linear equatioans

x = 6 - y

3x = 20 - 4y

Solution : SUBSTITUTION METHOD

x = 6 - y                  -------------(1)

3x = 20 - 4y            -------------(2)

Substitute (1) into (2)

3(6 - y) = 20 - 4y

18 - 3y = 20 - 4y

-3y + 4y = 20 - 18

y = 2

From (1) subtitute y = 2

x = 6 - 2

x = 4