Are the lines 3x+4y=-12 and 6x+2y=6 parallel?

Hi

two lines are parallel only if they have the same slope.

So :  3x+4y = 12

         4y = 12 -3x

           y =  12/4 - 3x/4

           y =   3 - 3/4 X

          y =   -3/4 X +3

Slope is   -3/4

and   6x+2y = 6

               2y = 6 -6x

                  y =  6/2 - 6x/2

                 y =   3 - 3X

                 y =  -3X +3

Slope is = -3

As  -3/4 ≠ -3  then   the two lines are not parallel.

the circle one

you can't solve x because it is 2 linear equation and you only have one equation