Question

The graph of the equations 2x – y – 4 = 0 and x + y + 1 = 0 intersect each other in point P(a, b), then find the coordinates of P?

Answer 1

The given equations are

2x – y – 4 = 0

∴ y = 2x – 4

x	0	2	3	4
y	– 4	0	2	4
(x, y)	(0, – 4)	(2, 0)	(3, 2)	(4, 4)

x + y + 1 = 0

∴ y = – x – 1

x	0	1	2	–1
y	–1	–2	–3	0
(x, y)	(0, –1)	(1, –2)	(2, –3)	(–1, 0)

The two lines intersect at P(1, –2).

∴ The coordinates of P are (1, –2).