DETERMINE whether the 2 lines are parallel, perpendicular, or neither.

9x+2y=-10

y=-9/2x-6

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- Jul 2nd 2009, 12:28 PMInsignia21Help
DETERMINE whether the 2 lines are parallel, perpendicular, or neither.

9x+2y=-10

y=-9/2x-6 - Jul 2nd 2009, 02:09 PMKasper
Hey Insignia21,

A good piece of information to know here is that if 2 lines are parallel, they will have the__same__slope, and if they are perpendicular, the slopes will be__negative reciprocals of one another__.That said, we can see clearly the the slope of is . We know this from knowing the formula for a straight line where

So we know that for to be parallel, it must have a slope of , and if it is perpendicular, it must have a slope of .

Now we must solve the first equation for y and find the slope, and then compare it to the above.

And from this we can see that the slope of

is which when compared above is not the same or the negative reciprocal of the second equation. Therefore the 2 lines are__neither__parallel or perpendicular.

Does this help? - Jul 2nd 2009, 06:18 PMHallsofIvy
Well done, Kaspar!

**Up to**this point!

Quote:

**2**so this is

and the slopes**are**the same!

Quote:

And from this we can see that the slope of

is which when compared above is not the same or the negative reciprocal of the second equation. Therefore the 2 lines are__neither__parallel or perpendicular.

Does this help?

- Jul 2nd 2009, 06:20 PMKasper
Oh dear. Wow. Thanks for that clarification!