Question

Write the equation of the line that is perpendicular to y= 1/4x and passes through the point (2,-5)

Answer 1

So you'll first be finding the slope and then after you find the slope, you use the point-slope form equation. It also asks for a perpendicular slope. A perpendicular slope is when you take the negative reciprocal of your current slope. So if you had a slope of 2, the perepndicular slope would be -1/2. That being said, the initial equation ius y=1/4x, which is the in the form of y = mx + b. If m is the slope, then in your equation, 1/4 is the slope. So knowing that the perpendicular slope means takign the negative reciprocal, do you know the point-slope form in order to do the rest of the work?

Answer 2

no i dont

Answer 3

is that the total equation....y = 1/4x ??

Answer 4

yes

Answer 5

hold on.....@gypsy1274 .....can you take a look at this

Answer 6

@gypsy1274

Answer 7

@campbell_st ...help

Answer 8

do you do it the same way even though there is no y intercept psymon ?

Answer 9

well, point slope form is y - y1 = m(x-x1) So the idea is to know what your perpendicular slope is and then just plug in numbers. And the y-intercept isnt important, just that number in front of x.

Answer 10

ok......wasn't sure....thanks

Answer 11

Mhm. So if the slope is 1/4, then the perpendicular slope would be flipping it and making it negative (negative reciprocal). Then that value becomes your new "m" in the point slope form equation I listed. The y1 and x1 are just the cooridnates of the point you were given.

Answer 12

An easy way to do this question is

slope of the given line is m = 1/4

the perpendicular has a slope that is the negative reciprocal

m = -4

the slope intercept form is

y = mx + b

substitute you slope. the substitute the information from your point (2, -5)
which is x = 2 and y = -5 to find the value of b.

Answer 13

oops should read slope for the perpendicular... into y = mx + b

Answer 14

so how would you write out the equation ? -4+-5 ?

Answer 15

y = -4x + b

substitute x = 2 and y = -5

-5 = -4*(2) + b

solve for b

Answer 16

-1.6 ?

Answer 17

nope

Answer 18

-5 = -8 + b
-5 + 8 = b
can you take it from here ?

Answer 19

y+5 = -4(x-2), then you multiply and solve from there. That was just what I plugged into the point slop form equation. You would get what they're getting as well.

Answer 20

thats true

Answer 21

i add -5 and 8 ?

Answer 22

that is your y intercept......so yes

Answer 23

y = -4x + b (b is your y intercept)

Answer 24

so 3 is the y

Answer 25

no...3 is the b

Answer 26

your answer is y = -4x + 3

Answer 27

or psymon's way... (2,-5)
y - y1 = m(x - x1)
y - (-5) = -4(x - 2)
y + 5 = -4x + 8
y = -4x + 8 - 5
y = -4x + 3

Answer 28

its wrong ...

Answer 29

huh.....really ?

Answer 30

yea i just tried it

Answer 31

@campbell_st ......she said it was wrong

Answer 32

so y = -4x + 3 is wrong, what about 4x + y = 3

or y + 5 = -4(x - 2)

any of those are correct.

Answer 33

true.....it could be in Ax + By = C form.....or slope intercept form

Answer 34

there all wrong ?

Answer 35

@campbell_st

Answer 36

what are we doing wrong ?

Answer 37

@xoxox123 ok... can you now go and check the question is correctly typed... as based on the information provided... the solutions are correct...

Answer 38

Yes I'm positive the problem is right!! looked over it @campbell_st

Answer 39

ok.... the text answer or website answer is incorrect...

Answer 40

no this website makes sure you get it right so your problem is wrong

Answer 41

I am gonna go with campbell......it looks correct to me

Answer 42

it looks correct to me too but, i dont know why its counting it wrong

Answer 43

is their answer choices ?

Answer 44

nope. written response

Answer 45

@texaschic101

Answer 46

yes......I don't know what to say

Answer 47

@phi .......please look at this

Answer 48

hes offline lol

Answer 49

oops

Answer 50

ok...here is a graph of the 2 lines, with an angle shown.

it shows your line from the question, the point and the angle between the lines as 90, which means perpendicular...

Answer 51

so what solution did they give you...?

Answer 52

Solution ?

Answer 53

yes... you said our answer was wrong... so what solution did your website give..?

Answer 54

It doesn't give you an answer when you get it wrong.. it just tells you its wrong then you have to try it again

Answer 55

lol... unless the site is wrong.... then you'll enter wrong answer till infinity and beyond.......good luck...

Answer 56

the website isn't wrong? How is it wrong if I've been working on it for a month and have been entering answers in it? that i get right! so you made a mistake in your answer

Answer 57

I just don't see the mistake......I would post this question again and see what other people say

Answer 58

good luck :)

Answer 59

I think they will say the same thing

Answer 60

we shall see ..

Answer 61

ok.... so you have an algebraic solution to your problem, yo have a graphical solution to your problem, 3 unrelated people get the same solution using the information you have posted...

and in every case the solution to the information provided is y = -4x + 3

so perhaps posting the question again, going and reviewing your work on perpendicular lines and equations of straight lines may help you get a solution. Or perhaps the website as mis-typed the answer.