Question

find the equation of the line trough the given points.(3, 1) and (1, 3) state the answer in y=mx+b

Answer 1

y = -m + c

Answer 2

Slope m = (y-y1)/(x-x1) so: (3-1)/(1-3) = -1

y = (-1)x+4

Answer 3

y = -x + 4

Answer 4

can you do all the steps so I can understand what Im doing wrong

Answer 5

these are points on a slope

Answer 6

y-y1=m(x-x1) This one

Answer 7

1 = 3m + C - equation 1
3 = m + C - equation 2

rearrange eq 2, u will get

m = 3 - C

substitute this into equation 1

then you will get 1 = 3(3-C) + C
1 = 9 - 3C + C
1 - 9 = -3C + C
-8 = -2C
C = 4

then substitute C = 4 into general equation of a straight line
you will get y = mx + 4

then substitute any point (3,1) or (1,3) into y = mx + 4

i use (3,1)

1 = 3m +4
1-4 = 3m
-3 = 3m
m = -1

substitute value C and m.

y = mx + C
y = (-1)x + 4.

Answer 8

I guess i was totallly wrong. Thanks this makes more scence to me then the way I was trying to do it.

Answer 9

I don't use the point slope formula
or do I use the equation of a line trough two points

Answer 10

You already have 2 points so I'd just plug those into the point-slope formula to find m:
(y-y1) = m(x-x1)

It doesn't matter which pair of coordinates you choose to be x,y or x1,y1...as long as you are consistent throughout the problem.

For my example, I'll go with x,y = (1,3) and x1,y1 = (3,1).

So it's: (3-1) = m(1-3)

To find m, divide both sides by (1-3). You'll end up with m = -1.

Now you just need to convert the answer to slope-intercept form which is:
y = mx + b

So it's: 3 = (-1)1 + b

b must = 4

Answer 11

Which gives you y = -1x + 4

Answer 12

ok i totally get that much easier thanks.