What is the equation of a line that is perpendicular to the line whose equation is y = x + 2?
(WILL GIVE MEDAL)

A. x + y = 5
B. y - x = -1
C. 2x + y = -2
D. y - 2x = 3

Question

What is the equation of a line that is perpendicular to the line whose equation is y = x + 2?
 (WILL GIVE MEDAL)

	A.	x + y = 5
	B.	y - x = -1
	C.	2x + y = -2
	D.	y - 2x = 3

anonymous · Answer

To find perpendicular lines you take the inverse of the slope:

m = 1 ->TAKE INVERE -> m = -1 of new line

solomonzelman · Answer

In this case it is -1, my bad, sorry...

solomonzelman · Answer

put A, B, C and D into y=mx+ from, which has a slope of -1?

anonymous · Answer

oh so B?

solomonzelman · Answer

No, you forgot to put it into a y+mx+b, (or the standard) form.

solomonzelman · Answer

For A , to put it into a standard form subtract x from both sides.

anonymous · Answer

sorry im going blank on how to do this. lol im feeling stupid right now

solomonzelman · Answer

I'll show you how to do the D, K?

solomonzelman · Answer

y - 2x = 3
y - 2x+2x = 3+2x (b/c you need to eliminate the y by itself)
y=2x-3

Since we know that the slope of a perpendicular line is the multiplicative inverse times '-1'
(for line with slope a, perpendicular line will have a slope of  -1/a), and in this case it is 1/1 times -1 which is equal to -1, therefore the answer choice D is not a correct answer, because  it has a slope of 2.
@jazmin_d, good?

anonymous · Answer

Oh ok i understand but then again im still trying to figure it out. LOL. but i get what your saying. it makes sense.

solomonzelman · Answer

OK put choices A, B and C into the same form as I put D into.