I need help please (math)?

Question

i need help finding the equation of a line?!?

i've looked it up on the web and i still dont get it

1.(2,7) (5,10)

2.(-1,2) (1,2)

i would like to know HOW to do it please

Answer 1

You could also use the point-slope formula: y – y1 = m(x – x1).

For number one y would be 7 and y1 would be 10.  x would be 2 and x1 would be 5.  The equation would look like this:

7-10 = m(2 - 5)

-3 = m-3

m=6

Now plug the m back in and only y1 and x1.

y - 10 = 6(x - 5)

y - 10 = 6x - 30

y = 6x - 20 is the answer for the first question

For the 2nd one, I'll use the slope intercept formula: y=mx+b

First, we need to find the slope:

2-2/-1-1 = 0/-2; m = -2

y=-2x+b, insert one of the points into the formula. I'll use (1,2)

2 = -2(1)+b

2 = -2 + b

4 = b

So the formula would be y = -2x + 4

Answer 2

the equation of a line is often written in the form y = mx + b where the m is the slope and the b is the y-intercept

in order to find the slope when you know two points, we use:

m = (y1 - y2)/(x1 - x2) ...we plug in our values for x's and y's

m = (7 - 10)/(2 - 5)

m = -3/-3

m = 1

now that we have the slope, we put that in: y = 1x + b

but we don't know what b is yet so we take one of our points and put it into our new equation that has the slope in it:

7 = 1(2) + b

7 = 2 + b

5 = b

now we have m and b so our equation is: y = 1x + 5

y = x + 5

Question 2

find slope

m = (y1 - y2)/(x1 - x2)

m = (2 - 2)/(-1 - 1)

m = 0/-2

m = 0 ...a slope of zero means that our line is going straight across (horizontally)

plug that into our equation y = 0x + b

put one of our points in so we can find b

2 = 0(-1) + b

2 = b

so our equation is y = 2

Answer 3

you have to do mx+b=y

m=slope

x=x

b=y-intercept

y=y

if you know how to find the slope and y-intercept you'll get it

if not email me