Question

Use graph paper for this question. Take 2 cm = 2 units on x-axis and 2 cm = 1 unit on y-axis.
Solve graphically the following equation:
3x + 5y = 12; 3x - 5y + 18 = 0 (Plot only three points per line)

Answer 1

3x + 5y = 12
⇒ 3x = 12 - 5y
x = `(12 - 5y)/(3)`

The table for 3x + 5y = 12 is

X	4	- 1	- 6
Y	0	3	6

Also we have
3x - 5y + 18 = 0
⇒ 3x = 5y - 18
⇒ x = `(5y - 18)/(3)` 
The table for 3x - 5y + 18 = 0 is

X	- 6	4	- 1
Y	0	6	3

Plotting the above points we get the following required graph:

From the above graph, it is clear that the two lines 3x + 5y = 12 and 3x - 5y + 18 = 0 intersect at the point (-1, 3)