# Homework Help: Tangent to y=e^x

1. Dec 1, 2011

### iRaid

1. The problem statement, all variables and given/known data
Find an equation for a line that is tangent to the graph of y=ex and goes through the origin.

2. Relevant equations

3. The attempt at a solution
y'=ex

That's about all I can think of. I don't know how to make the tangent line go through the origin. Can someone lead me in the right direction?

Last edited: Dec 1, 2011
2. Dec 1, 2011

### Ray Vickson

At any point (x,y) on the graph, how would you compute the slope of the tangent line?

RGV

3. Dec 1, 2011

### iRaid

Find the derivative at that point.

4. Dec 2, 2011

### HallsofIvy

And you have already said that the derivative is again $e^x$.

So the tangent line to $y= e^x$ at $x= x_0$ would be $y= e^{x_0}(x- x_0)+ e^{x_0}$. Now, what must [itex]x_0[/b] be so that goes through (0, 0)?

5. Dec 2, 2011

### iRaid

0? Not really sure..