htdocs/resources/maths/pure/exponentials.gmi
2025-03-31 16:41:54 +01:00

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# Exponential Graphs
=> differenciation.gmi You should understand differentiation before reading this section
Exponential graphs are those in the form of y = k^(x)
they should look like this:
y
|
| |
| |
| |
| |
| |
| |
| _-
| ___--
|---------___________ x
As you can see, the line curves upwards, increasing in gradient costantly.
It's also interesting to note that all exponential graphs (without a specified y intercept), intersect y at 1 as n^0 === 1
If you draw the gradient graph of an exponential, you get another exponential graph, they are usually slightly different to the original graph,
for instance, the gradient graph of 2^x is slightly shallower than 2^x
and the gradient graph of 3^x is slightly steeper than 3^x,
As you can see, the gradient graph and initial graph must cross at a certain value between 2 and 3
that value is about 2.718, the gradient graph 2.718^x is exactly the same as 2.718^x, we call this value e.
Similar to pi, the number e actually goes on forever, I just rounded it to 2.718, the first 10 digits are 2.718281828.
So e is a special number because if you differenciate it, you get the same value:
```
y = e^x
dy/dx = e^x
y = e^kx
dy/dx = ke^kx
```