Plot isn't showing the full range of my function

Question

I have this function that I want to graph

V[x_] = (1 (1 - E^(-9.8 x)))

But when I graph it it shows a function that is not correct

It should pass through origin.

If anyone could help, I would be much obliged.

Answer 1

To your question itself, in executing Plot you have specified the domain ({x, 0, 5}), but not the range. So, Plot tries to show the most interesting parts of the function. To show everything, you change the range, you need to add the option PlotRange, e.g.

Plot[V[x] (1 (1 - E^(-9.8 x))), {x, 0, 5}, PlotStyle -> Red, PlotRange -> All]

With regards to your code itself, a couple of points. First, Plot does not need to be wrapped in Show to display. Show modifies an existing Graphics object, by either combining multiple ones together and/or modifying the options. Second, generally when declaring a function, you want to use SetDelayed (:=) not Set (=), c.f. this question.

V[x_] := (1 (1 - E^(-9.8 x)))

Set is useful when you need to capture a long calculation, but usually SetDelayed captures the idea of what a function is better. Third, in your argument to Plot you multiply V[x] by (1 (1 - E^(-9.8 x))), or V[x], which I do not think is what you intend.

All together,

Plot[V[x], {x, 0, 5}, PlotStyle -> Red, PlotRange -> All]

which is not much different than your original plot (not shown).