That's the product rule, not the chain rule.
If x=1, then the slope at that point is
Now, use your given points in y=mx+b to find the line equation.
The equation is with the point
I used the chain rule (I hope I used it correctly)
The problem is I don't know how to find the equation for the tangent line to the curve at the given point.
Thus the tangent line at x = 1 has a slope of and touches the curve at the point . (There are a couple of 1/e's floating around. Make sure you keep track of them.)
So your line equation, becomes
at the point .
Plug this x and value into the line equation and solve for b.