# Homework Help: Help with secant line

1. Oct 4, 2012

### sasuke07

1. The problem statement, all variables and given/known data
Find the slope of the line that joins P (0,2) and Q (x, 2^x+1) for x ≠0. type the expression using x as a variable.

2. Relevant equations
Rise over Run?

3. The attempt at a solution
I have a picture of the graph but i don't really know what to do, Please help.
I graphed it at x= -3, -2 and -1 cause that was part 1
Okay so i just had a thought in my mind. So we can use limits to find the slope of the secant line, So would i use The limit of 2^x+1 as x approaches 0. But then the slope would be 1, And how would i write the expression in terms of x.
So for when x=-1 the rise/run is .5/1
x=-2 rise over run is .75/2
and when x=-3 rise over run is .875/3
but now how would i do the expression part?

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Last edited: Oct 4, 2012
2. Oct 4, 2012

### Staff: Mentor

need to show some work, why not compute the slope as you said rise over run

3. Oct 4, 2012

### bonfire09

Just rewrite Q (x, 2^x+1) as Q(x)=2^x+1 and find your secant line at that point.

Last edited: Oct 4, 2012
4. Oct 4, 2012

### SammyS

Staff Emeritus
Given two points on a line, do you know how to get the slope?

5. Oct 4, 2012

### sasuke07

So for when x=-1 the rise/run is .5/1
x=-2 rise over run is .75/2
and when x=-3 rise over run is .875/3
but now how would i do the expression part?

6. Oct 4, 2012

### SammyS

Staff Emeritus
Now find the slope for the line passing through points (0,2) and (x, 2x+1 )

Yes, there will be a variable involved.

7. Oct 5, 2012

### sasuke07

couldn't i just use the limit of 2^x+1 as x approaches 0 to find the slope?

8. Oct 5, 2012

### SammyS

Staff Emeritus
The slope of what?

9. Oct 5, 2012

### sasuke07

the slope of the secant line

10. Oct 5, 2012

### sasuke07

doesn't the secant line connect those 2 points, so cant i figure out the slope using limits

11. Oct 5, 2012

### SammyS

Staff Emeritus
You don't need to take any limits. You're finding the slope of a line, given two distinct points, one of which has coordinates given in terms of x.

12. Oct 5, 2012

### sasuke07

Thanks a lot for the help.