You should first recognize the shape of the curve - it's an exponential function, so its equation takes the form
for some constants <em>a</em>, <em>b</em>, and <em>c</em>.
The curve lies above the <em>x</em>-axis, so <em>a</em> must be positive.
The curve is defined everywhere (there are no discontinuities), so <em>b</em> must be positive.
As you move left to right, the function is increasing, so <em>c</em> must also be positive. But to make things simpler, let's assume <em>c</em> = 1.
When <em>x</em> = 0, the curve passes through the point (0, 1). In our equation, we have

so it follows that <em>a</em> = 1.
When <em>x</em> = 1, the curve approximately passes through the point (1, 4); so

so <em>b</em> = 4.
Then the equation of the curve might be
.