Question

Solve the following simultaneous equation graphically.
5x – 6y + 30 = 0 ; 5x + 4y – 20 = 0

Answer 1

Given:

5x − 6y + 30 = 0     ...(1)

5x + 4y − 20 = 0     ...(2)

Write in slope–intercept form (y = mx + c)

5x − 6y + 30 = 0

−6y = −5x − 30

`y = 5/6 x +5`     ...(From (1)

5x + 4y − 20 = 0

4y = −5x + 20

`y = -5/4 x + 5`     ...(From 2)

Points for first line

`y = 5/6 x +5`
x	y
0	5
−6	0

→ Line passes through (0, 5) and (–6, 0)

Points for second line

`y = -5/4 x + 5`
x	y
0	5
4	0

When plotted, both lines meet at (0, 5).

x = 0, y = 5:

In (1): 5(0) − 6(5) + 30 = 0

In (2): 5(0) + 4(5) − 20 = 0