Question

What is the equation for the line that passes through (1, -4) and is perpendicular to y = -2x +4?

Answer 1

I get y = 2x-6, but supposedly the answer is y=0,5x-4,5. I'm thinking the book is wrong. Thoughts?

Answer 2

what is the slope of given line y=-2x+4 ??
can u find slope ?

Answer 3

well, according to the formula y = kx + m, it should be 2, given that it's perpendicular to -2

Answer 4

the slope of y=-2x+4 is -2..
the slope of the perpendicular line is 1/2

Answer 5

since m1*m2 = -1 given m1 is perpendicular to m2

Answer 6

so now you have a slope and a point .. do you know how to find the line equation ?

Answer 7

Hmm, sorry how did you calculate the slope?

Answer 8

the slope of the given line is -2 right ?

Answer 9

yup

Answer 10

now slopes of perpendicular lines satisfies :
m1 * m2 = -1
now we know m1 = -2
-2 * m2 = -1
m2 = 1/2

Answer 11

Totally confused. We only have m1, which is 4, where does m1 *m2 = -1 come from??

Answer 12

m1 is -2 !!
m - represents slope

Answer 13

y=mx+n

Answer 14

m2 - is the slope of the perpendicular line that we are looking for

Answer 15

sorry if my letters\symbols are different from yours

Answer 16

ah, right, yeah I would have called that k :) I'll try this again...

Answer 17

ok now you have slope and a point so it should be easy for you

Answer 18

gah, nope...

Are you sure m1*m2= -1?

If I draw (2/1) and (-2/1) they're perpendicular (unless I'm drawing them wrng), but 2 * (-2) = -4

Answer 19

yes.. im sure http://www.purplemath.com/modules/slope2.htm

Answer 20

lets do this together ..
we found m2 = 1/2
now we have the point (1,-4)
so the perpendicular line equation is :
y2 = -4 + 0.5(x-1)
y2 = -4 + 0.5x -0.5 = 0.5x -4.5x

Answer 21

allright, I'm convinced :)

thanks for you help

time for a break for me I think

Answer 22

yw