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


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