A point on the line x + y = 0 can be represented as (a,-a).
(a,0)
(0,a)
x + y = 0 ⇒ x = - y or y = - x If x = a, y = -a ∴ Any point on the line x + y = 0 can be represented as (a,-a)
A point on the line x + y = 0 can be represented as
Any point on the line represented by x−2y=0 can be written as (2a,a).
Any point on y = x can be represented as (a,a)