Question

Which lines are perpendicular to the line y – 1 = 1/3(x+2)? Check all that apply.

y + 2 = –3(x – 4)
y − 5 = 3(x + 11)
y = -3x – 5/3
y = 1/3x – 2
3x + y = 7

Answer 1

A line that is perpendicular to another one has a slope that is the opposite reciprocal of that slope. This means that it is the opposite sign and 1 over the slope. With this in mind, the opposite reciprocal of 1/3 is -3, so we are looking for lines with a slope of -3.

The first, third, and fifth equations have slopes of -3. This is seen by the fact that it (-3) is being multipled by x in the equation when y is the only variable on one side or isolated.

I hope this helps :D