Question

Solve the following simultaneous equations by using graphical method : x + y = 6;  x – y = 4.

Answer 1

First we find three solutions for each equation and make tables.
x + y = 6 ⇒ y = 6 – x
x – y = 4 ⇒ y = x – 4

x+y=6
x	1	-1	0
y	5	7	6

Now, plot the points (1, 5), (–1, 7) and (0, 6) and draw the line passing through them

x-y=4
x	1	-1	0
y	-3	-5	-4

Now, plot the points (1, –3), (–1, –5) and (0, –4) and draw the line passing through them.

Thus the point of intersection of two lines is (5, 1).
Hence x = 5 and y = 1 is the solution of the given equations.