Math help please...?

Question

Ok, I'm having trouble understanding y-y1=m(x-x1). I have two problems I can't complete and your help is appreciated!!

Find an equation of the line that passes through the point and has the indicated slope.

(4,0) m= -1/3
and
(6,-1) m=undefined

please provide steps so that I can learn how to do these...thanks a million!!!

the answers in the book are:

For (4,0) m=-1/3, x+3y-4=0
and
For (6,-1) m=undef., x-6=0

I don't understand how they derived these answers...

Answer 1

It's a line
m is the slope.
YAY for algebra.

Answer 2

First, plug in the x, y, and the slope values into the problem. For example #1 x1=4, y1=0, and the slope is 1/3. So that means y-0=1/3(x-4). Therefore, y-0=1/3x-4/3. Next, get y by itself by adding zero to both sides and y=1/3x-4/3

Answer 3

I can only help you with the first one:

you need y-y1=m(x-x1) to get the equation of the line. y1 and x1 are the coordinates of a point on that line, m is the slope of the line. So for the first one, plug in x1=4 and y1=0 and m=-1/3:
y-0 = -1/3(x-4)
simplify:
y=-x/3 + 4/3

The second one you do simiilar, only I don't get the slope is undefined part.

Answer 4

for this equation you must use slope intercept form which is y=mx+b
so you plug in the two points and the slope- 0=4(-1/3)+b and solve for b
once you find b your equation will be y= -1/3x + whatever you found B to be

and undefined slope simply means that the line is vertical...meaning the ling only passes through the x intercept.....so you take the x point which is 6 and your equation is x=6

Answer 5

y=mx+b
y= -1/3x+b input the slope
0= -1/3(4)+b input the coordinates
0= -4/3+b find b
4/3=b