Question

Which pair of lines are perpendicular?
A.
y
=
1
4
x
and
y
=
−
4
x
B.
y
=
1
4
x
and
y
=
4
x
C.
y
=
1
4
x
and
y
=
1
4
x
D.
y
=
1
4
x
and
y
=
−
1
4
x

Answer 1

A. Because slopes are 1/4 and −4, and (1/4)(−4) = −1, so the lines are perpendicular.