Exponential Curves

Changing a

Now consider the effect that the value of *a* has on the exponential curve. The value of *a* determines where the curve crosses the y-axis. The graph below displays the curves of three exponential functions with the same base, but with varying positive values of *a*. Notice that the y-intercept is the same value as *a *and that the overall shape of the curve does not change. When *a* is positive the curve will increase from left to right.

What happens to the curve when *a* is negative? The following graph demonstrates the effect of a negative value for *a*. The curve still intersects the *y*-axis at the value of *a*, but the curve has now been reflected across the *x*-axis and the function decreases from left to right.