SOLUTION: The question asks to find the y intercept and slope of the line that represents the table. The table looks likes this.. Time (min) | 5 | 10 | 15 | 20 | 25 | Charge.($) | 8 | 1

Algebra ->  Linear-equations -> SOLUTION: The question asks to find the y intercept and slope of the line that represents the table. The table looks likes this.. Time (min) | 5 | 10 | 15 | 20 | 25 | Charge.($) | 8 | 1      Log On


   



Question 455711: The question asks to find the y intercept and slope of the line that represents the table. The table looks likes this..
Time (min) | 5 | 10 | 15 | 20 | 25 |
Charge.($) | 8 | 13 | 18 | 23 | 28 |
I found the slope, but I do not understand how to find the y-intercept

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
Time (min) | 5 | 10 | 15 | 20 | 25 | 
Charge ($) | 8 | 13 | 18 | 23 | 28 |

I'll show you three ways to find it.

Plot the 5 points on a graph:



Draw a line through them



Now you can see that the green line crosses the y-axis at 3,

That means the y-intercept is the point (0,3).

Another way to do it is to look at your list:

Time (min) | 5 | 10 | 15 | 20 | 25 | 
Charge ($) | 8 | 13 | 18 | 23 | 28 |

Notice that the times are spaced out in steps of 5 minutes
starting with 5

Also notice that the charges are spaced out is steps of 5,
starting with 8.

Now suppose we wanted to put in a point before (5,8). It 
would have to be (0,3)

Time (min) | 0 | 5 | 10 | 15 | 20 | 25 | 
Charge.($) | 3 | 8 | 13 | 18 | 23 | 28 |

That's because the point before the first one would have to be
gotten by subtracting 5 from 5 getting 0 and 5 from 8 getting 3.
So the y-intercept is (0,3)

You can also do it by first finding the slope using the first two
points, (5,8) and (10,13) and then using the point-slope form.

m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29+=+%2813-8%29%2F%2810-5%29+=+5%2F5+=+1

y-y%5B1%5D=m%28x-x%5B1%5D%29

y-8=1%28x-5%29

y-8=x-5

y=x%2B3%29

Now the y-intercept is gotten by substituting x=0

y=0%2B3%29

y=3%29

So the y-intercept is (0,3).

Edwin