Question

A line passes through the point (–1,–2) and is perpendicular to the line with the equation y= –x – 1. What's the equation of the line?

Question 16 options:

A) 
y = x – 5

B) 
y = –x + 3

C) 
y = –x + 7

D) 
y = x – 1

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Answer 1

B) y = -x - 3

Explanation:

slope = -1

y = mx + b

-2 = -1(-1) + b

-3 = b

y = -x - 3

Answer 2

D) y = x - 1

Explanation:

First we need the general equation of point slope form:

(y - y0) = m(x - x0)

Where y0 is the y coordinate and x0 is the x coordinate and m is the slope.

For the line to be perpendicular, we need the slope to be the negated opposite of the other equation. So the negated opposite of -1 is 1.

So our m = 1, y0 = -2, and x0 = -1. Now let's plug this into the equation and reform the equation into slope-intercept form

(y - (-2)) = 1 (x - (-1))

y + 2 = 1 (x + 1)

y + 2 = x + 1

y = x - 1

So the equation of the line that goes through the point (-1,-2) and is perpendicular to the line y = -x -1, is y = x - 1.

Cheers.