From the choices given below, choose the equation whose graph in Fig. 13.13.
(i) y = x
(ii) x+y=0
(iii) y=2x
(iv) 2+3y=7x
[Hint: Clearly, (-1,1) and (1,-1) satisfy the equation x+y=0]
From the graph, the line passes through (1, - 1) and (-1, 1)
(i) y = x
⇒ 1 = -1 which is not true
(ii) x + y = 0
⇒ 1 – 1 = 0
⇒ 0 = 0
Also, - 1 + 1 = 0
⇒ 0 = 0
Thus x + y = 0 is a equation
(iii) y = 2x
⇒ -1 = 2 which is not true
(iv) 2 + 3y = 7x
⇒ 2 – 3 = 7
⇒ -1 = 7 which is not true