Question

How to find "m" and "c" in an equation of a line if you know x and y?

y = mx + c

Answer 1

when you have 2 unknowns, you will need two types of information.

case 1) when two points are given,
first find "m"
then plug it in the above equation.
then use any of those two points to get the value of "b"

Answer 2

case 2) information concerning another line.
like line is parallel or normal gives you "m" directly
then use it like above case.

Answer 3

if you have a particular question, go ahead

Answer 4

But c and m are not known to me so I have 2 different uknown numbers how do I find them with only y and x to be known

Answer 5

ok. lets take an example. ask a particular problem.

Answer 6

4 = m3 + c what's m and c?

Answer 7

i would say, you simply cannot find m and c
you'll need 2 pairs of points (2 values of x and y each) to get the value of m and c.

Answer 8

(4-2)=m(6-3) + c what is it now?

Answer 9

Was that the tow pairs you were talking about?

Answer 10

so, 2 points you considered are 4,6 and 2,3 ??

Answer 11

yeah

Answer 12

then you have 2 equations and 2 unknowns, you can find m and c
1st equation, using the point 4,6
6 = 4m+c

can you form 2nd equation ?

Answer 13

3 = -2m + c ?

Answer 14

why -2 ?
x=+2, right ?
so in y=mx+c
3=2m+c
right ?

Answer 15

Yes true that i am sorry

Answer 16

so, 2 equations, 2 unkowns, will give you m and c, can you find them now ?

Answer 17

3=2m+c
6 = 4m+c

6-4m=c
3 = 2m+6-4m

Answer 18

good, go ahead.

Answer 19

you'll be able to find 'm' easily from that.
then just plug in value of m in any of the equation to get c

Answer 20

So if I find the value of c and m like this it will be the same value of m and c for
the whole aequation meaning this (4-2)=m(6-3) + c ?

Answer 21

firstly, you've interchanges x and y
shouldn't it be (6-3) = (4-2)m+c ??
and yes the values of m and c would be the same because you have subtracted the equation.
nevertheless you won't be able to find m and c using just that 1 equation...