Are the lines y=8x-5, y=1/8x+1y=8x5,y=18x+1 and 8x+y=28x+y=2 parallel or perpendicular?

1 Answer

The second and third lines are perpendicular

Explanation:

If you restructure the third equation by subtracting 8x8x from both sides, you'll get

y=-8x+2y=8x+2

With

y=mx+b" "y=mx+b [here m = m=slope]

you know the slope of all three lines: 88, 1/818, and -88, respectively.

Two lines are perpendicular when their slopes are negative reciprocals . You can see that two slopes are negative reciprocals if -11 divided by one slope equals the other slope.

Because -11 divided by -88 equals 1/818, you know that the second and third equations have negative reciprocal slopes, therefore they are perpendicular.

The first equation isn't perpendicular to either of the other two lines because -11 divided by 88 is -1/818, which does not match any of the other slopes. It isn't parallel either (parallel lines have the same slope).