Question

What is the equation of the line that is perpendicular to -x + y = 7 and passes through (-1, -1)?

A.
-x + y = 2
B.
-x – y = 2
C.
x – y = 2
D.
-x – y = 0
E.
x + y = 0

Answer 1

E because the slope is opposite

Answer 2

We have y = x + 7; the slope of this line is m1 = 1;

Because the lines are perpendicular, we have m1 · m2 = - 1;

Then m2 = -1;

The equation of the second line, which passes through (-1 ,-1) and have the slope m2 = -1 is:

y - (-1) = (-1)( x - (-1));

y - 1 = (-1)( x + 1 );

y - 1 = -x - 1;

y + x = 0;

The correct answer is E. x + y = 0;

Explanation: