Which line is perpendicular to the line x – y = 1

A. x + y = 1

B. x + 2y = 1

C. 2x + y = 1

D. x – y = 7

E. 5x + 2y = 10

Put each each answer in slope-intercept form. Meaning solve for y. Then multiply the slopes and if the answer is -1 then they are perpendicular.

The slope intercepth form for x-y =1 is y= -x-1

Slope intercept form for the answers
A. y = -x +1
B. y = -1/2x +1/2
C. y = -2x + 1
D. y = x - 7
E. y = -5/2x +5

In the equation y = mx + b the slope is m. Multiply the slopes in each of the answers indviidually with the equation in the question and if you get -1 as your product they are perpendicular to each other.

Therefore your answer has to be A.

When you rearrange the equation to solve for y to get y=x-1.

A line perpendicular to another line has a slope that is the negative reciprocal of the first line

The slope would then have to be -1 for a line to be perpendicular to the first line and is therefore

choice A.

For lines to be perpendicular to one another their respective slopes are the negative reciprocal of one another. Therefore, if we let m1 represent the slope of the first given line and m2 equal to the slope of the second line then we determine that:

x - y = 1
and solving for y,
- y = - x + 1
dividing both sides of the equation by -1, we obtain
y = x - 1 this equation is now in the proper form of the slope-intercept form of a line
or y = m1x - b here m1 = 1.

To find the value of m2,

m1 * m2 = -1
m2 = -1 / m1
m2 = -1 / 1 = -1

The line therefore that is perpendicular to the line x - y = 1 is,

( y - y2 ) = m2 ( x - x2)
( y - 1 ) = -1 x - 0
y = -x + 1

x + y = 1 Answer: A .

For additional information, please see also:

http://en.wikipedia.org/wiki/Linear_equa…
http://www.purplemath.com/modules/solvel…
http://www.studygs.net/equations.htm
http://www.mathsisfun.com/algebra/linear…
http://mathworld.wolfram.com/LinearEquat…
http://en.wikipedia.org/wiki/Slope

x - y = 1 => y = 1 - x

Slope of this line is -1 and slope of perpendicular line is 1, so option D makes the most sense

A :)

A