Is -2 perpendicular to y=2x+1
we have
the first equation is y=-2
is a horizontal line (slope is zero)
the second line is y=2x+1
the slope is m=2
Remember that
If two lines are perpendicular, then their slopes are opposite reciprocal
so
A line perpendicular to y=2x+1
must have a slope equal to m=-1/2
therefore
answer is
are not perpendicular