Question

A line passes through (7,2) and (11,-14). Write the equation of the line in general form.
A.
4x + y = 26
B.
4x + y = 30
C.
4x - y = 1
D.
4x - y = 26

Answer 1

firstly, you want to work out the gradient can you do so?

Answer 2

Whats a gradient?

Answer 3

its the slope

Answer 4

okay so try using this equation \[slope = \frac{ y - y1 }{ x - x1 }\]

Answer 5

7-11?

Answer 6

yes thats the bottom part of the fraction, what do you think will go on the top?

Answer 7

2-14

Answer 8

close, its actually 2 - (-14)

Answer 9

which becomes 2 + 14

Answer 10

but now we can put the bottom and top of our fraction together to simplify, what would you get?

Answer 11

-1/4

Answer 12

not exactly... \[\frac{ 2--14 }{ 7 - 11 }\]

Answer 13

then -4

Answer 14

yup thats right and we can now sub this into the equation \[y - y1 = m(x - x1)\] so try this and post up what you get

Answer 15

idk where to substitute it in..

Answer 16

like i dont get the whole letters with math thing..

Answer 17

A point that was given to you

Answer 18

For the x1 and y1

Answer 19

yea so remember your slope = m (so thats the -4 you just worked out) and (x1, y1) you can choose to either be (7,2) or (11, -14) (because both these points lie on the line

Answer 20

-4(7-11)...? I honestly don't know..

Answer 21

Plug the point into that equation for x1 and y1 so your 7 would be you x1 and 2 would be you y1 and out the slope in

Answer 22

And just x and y with nothing has nothing put in it, it just says x and y

Answer 23

just remember that we don't need to substitute anything in for x and y, only for x1 and y1 so the two possible sub ins you can do are..\[y - (2) = (-4)(x - (7))\] or \[y - (-14) = (-4)(x - (11))\]

Answer 24

either way when you simplify you should get the same answer, you can choose to sub in whichever point you want in the form as i have shown above (but you would like to pick the first option because that way you are dealing with smaller numbers

Answer 25

Do you know what to do now

Answer 26

No and i just give up because im still not understanding thanks for yalls help though

Answer 27

No dont give up what part is confusing you?

Answer 28

You can do it! :)

Answer 29

yeah which bit don't you understand? its okay we can help you :)

Answer 30

everything...math is so confusing to me no matter how much help i get..

Answer 31

So you have the point (x1,y1) it doesnt mattee which you choose so you have the point (7,2) so you 7 is your x1 and 2 is your y1

Answer 32

So now you plug that into your equation y-y1=m(x-x1) y1 and x1 is your point and y and x just stay the same, than plug in your slope too

Answer 33

You can do it 1Dfanatic I know you can