How does $A = P\cdot (1+r)^{n}$ becomes a graph function of $A = P\cdot (1+rt)$

Question

Accumulated simple interest function is:

$A = P\cdot (1+rt)$

When I tried to graph it, it fails.

After I read some articles, it tells that to graph simple interest function is a different equation:

$A = P\cdot (1+r)^{n}$

where $A$ is on Y-axis and $n$ is on X-axis.

And it works.

My question is:

How to find out a graph function from a function?

Answer 1

If you want to graph $A=P(1+rt)$ you multiply out the brackets first. $A(t)=P+Pr\cdot t$. Here t is on the $x$-axis and A on the $y$-axis. This is a linear function with the slope Pr and the intercept $P$.

I have added the linear function (simple interest) to your graph.