Which of the following lines are perpendicular to the line y=x in the

Question

Which of the following lines are perpendicular to the line y=x in the xy-plane?

I. x + y = 0
II. x + y = 1
III. x - y = 2

A. I only
B. II only
C. III only
D. I and II only
E. I, II and III

GMATinsight · Answer

The two lines are perpendicular if the product of their slopes is equal to -1 i.e.  m_1*m_2 = -1

Line y=x has slope = 1 .  
i.e.  1*m_2 = -1 
i.e.  m_2 = -1

i.e. line with -1 slope will be perpendicular to the given line

I. x + y = 0 slope = -1
II. x + y = 1 slope = -1
III. x - y = 2 slope = 1

Answer: Option D

ScottTargetTestPrep · Answer

Perpendicular lines have slopes that are negative reciprocals of each other. Since the given line has a slope of 1, any line perpendicular to it has a slope of -1.

Thus, we see that I and II are correct since we have y = -x and y = -x + 1, respectively (notice that each has a slope of -1).

Answer: D

LeoN88 · Answer

For two st. lines in the form y=mx +c
If mi*m2= -1 Then perpendicular
m1=m2 then parallel.

given line m=1

Let's find m for 
Line I (-1) Perpendicular
Line II (-1) Perpendicular
Line III (1) Parallel

Answer I+II

AbhaGanu · Answer

ScottTargetTestPrep  Even x - y = 2 has a negative slope right? Please correct the way I'm solving this: 
 
- y = -x + 2 = slope of -1

ScottTargetTestPrep · Answer

Solution:

x - y = 2 has a slope of 1, so it is not true that this line has a negative slope. Notice that the slope is the coefficient of the x-term only when the line is in the so-called “slope-intercept” form, which is y = mx + b. Your equation of -y = -x + 2 is not in the slope-intercept form because the coefficient of the y-term is -1 instead of 1. If you multiply each side of -y = -x + 2 by -1 to obtain y = x - 2, then the line is expressed in the slope-intercept form and the coefficient of the x-term (which is 1) is the (positive) slope of the line.

bumpbot · Answer

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Which of the following lines are perpendicular to the line y=x in the

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GMAT Problem Solving (PS) Questions

Which of the following lines are perpendicular to the line y=x in the

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