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How do you solve simultaneous linear LEARNING
equations in two variables? STANDARDS
Solve simultaneous
The simultaneous linear equations in two variables can be linear equations in
solved by using two variables using
(i) graphical method various methods.
(ii) substitution method
(iii) elimination method

11

Solve the following simultaneous linear equations by using graphical method.
x + y = 6 and 2x + y = 8

From the graph drawn, the y
point of intersection is (2, 4). 8
Thus, the solution is x = 2 6 2x + y = 8 The steps for solving
CHAPTER
6 and y = 4. 4 simultaneous linear
equations in two
2 variables using
x + y = 6
x substitution method:
0 2 4 6
12 Express one of the
variables in terms of
Solve the following simultaneous linear equations by using the other variable.
substitution method.
x – 3y = 7 and 5x + 2y = 1 Substitute the
expression into the
other linear equation.
x – 3y = 7 ............... 1
5x + 2y = 1 ............... 2 Solve the linear
Express x in
From 1, x = 7 + 3y ..... 3 equation in
terms of y.
Substitute 3 into 2. one variable.
5(7 + 3y) + 2y = 1
35 + 15y + 2y = 1 Substitute the value
35 + 17y = 1 obtained into the
17y = 1 – 35 expressed equation to
find the value of the
17y = –34 other variable.
–34
y =
17
y = –2
Substitute y = –2 into 3.
x = 7 + 3(–2)
= 1
Thus, x = 1 and y = –2.

140
Chapter 6

06 TB Math F1.indd 140 11/10/16 12:15 PM