line m (not shown)

Pick A

Line L

y = 2x

Line m is perpendicular to L


product of slopes = -1


M2 = -1/2

So the line m will be of y = -1/2 X +C

To get C, apply thge values of (x,y) : (0,0)
C = 0
So y = -1/2 X

Pick A

sanju09 wrote:In the x y-coordinate plane attached, line l contains the points (0, 0) and (1, 2). If line m (not shown) contains the point (0, 0) and is perpendicular to l, what is an equation of m?
(A) y = - ½ x
(B) y = - ½ x + 1
(C) y = - x
(D) y = - x + 2
(E) y = - 2 x

nah nah nah, the answer should be E
we can fine the slop of m by writing equation of l
since l contains the point (o,o) and (1,2) we have (y-0)/(x-0)=(1-0)/(2-0)
and we easily find l : y=1/2x
because slop (a) of m and l are perpendicular so
a.1/2=-1 or a =-2
so m must be E

diebeatsthegmat wrote:
nah nah nah, the answer should be E
we can fine the slop of m by writing equation of l
since l contains the point (o,o) and (1,2) we have (y-0)/(x-0)=(1-0)/(2-0)
and we easily find l : y=1/2x
because slop (a) of m and l are perpendicular so
a.1/2=-1 or a =-2
so m must be E

You made a mistake in calculating the line equation.
(y-0)/(x-0)=(1-0)/(2-0) is wrong
(y-0)/(x-0)=(2-0)/(1-0) is right.
So equation is y=2x.
Hence the line perpendicular will have slope -1/2
pick A.

One more thing. You need not calculate the line equation. Just calculate the slope and see which answer suits..

Hope this helps!!

Yep..I am with A too