Lines have infinite solutions

For what value of k the following system of linear equations wil have infinite solutions x-y+z=3, 2x+y-z=2 and -3x-2ky+6z=3

The value of C for which the pairs of equation cx-y=2 and 6x-2y=4 will have infinite many solutions.

Let the equations x+y+z=5,x+2y+2z=6,x+3y+lambda z=mu have infinite solutions then the value of lambda+mu is

System of linear equations in x,y,z 2x+y+z=1,x-2y+z=2,3x-y +2z=3 have infinite solutions which

Lines have only one solution

The equation pi^(x)=-2x^(2)+6x-9 has (A) no solution (B) one solution (C) two solutions (D) infinite solutions