Which of the following equation does not represent a pair of lines ?

Options

A. `x^2-x=0`
B. `xy-x=0`
C. `y^2-x+1=0`
D. `xy+x+y+1=0`

Answer

C

Explanation

`x^2-x=0`
`rArr x(x-1)=0`
`rArr x=0 and x=1`, which represent a pair of lines.
(b) `xy-x=0`
`rArr x(y-1)=0rArr x=0, y=1` , which represent a pair of lines.
(c) `y^2-x+1=0rArr y^2=(x-1)`, which represent a parabola.
Thus, it does represent a pair of lines.
(d) `xy+x+y+1=0`
`rArr x(y+1)(y+1)=0`
`rArr (y+1)(x+1)=0`
`rArr y=-and x=-1`, which represent a pair of lines.