Question

A line is perpendicular to y = -3x – 9 What is the slope of this perpendicular line?

Answer 1

Answer:

The correct answer option is D. 4.

Explanation:

We are given that a line is perpendicular to another line with the equation $y=-\frac{1}{4} x-9$. We are to find the slope of this perpendicular line.

We know that the in the standard equation of a line, $y=mx+c$, m is the slope of the line.

Also, the slope of a line perpendicular to another is the negative reciprocal of that line.

Therefore, the slope of this perpendicular line is 4.

Answer 2

Answer:

a. 1/3

In the picture- D. 4

Explanation:

The product of the gradients of perpendicular lines =-1

m1m2=-1

Given an equation of a line in the form y=mx+c, m is the gradient of the line.

For y= -3x-9, m=-3

m1m2=-1

-3×m2=-1

m2=1/3

The gradient of the perpendicular line is 1/3

For the question in the picture, y=-1/4x-9, m=-1/4

m1×m2=-1

-1/4m2=-1

m2=4

The slope of the line perpendicular to y=-1/4x-9 is 4