I really don't understand what I am doing. Needing help!
With graphing, tell whether the graphs of each pair of equations of each pair of equations are perpendicular.
1.y=7x-9 2.-3y=21x+7
slope=7 y=-7x-(7/3)
y-intercept=-9 slope=-7
y-intercept=-(7/3)
slope of #1 is 7
slope of #2 is ....
-3y = 21x + 7
y = -7x - 7/3
to be perpendicular, the slopes would have to be opposite reciprocals of each other
that is,
the 2nd would have had to have a slope of -1/7
no, they are NOT perpendicular