The exponential function crosses the -axis at the initial value and is decreasing because the base us a decay factor of The graph of this exponential function must be graph C. Read the function's value when in the graph.
The function's value is approximately equal to 200 when .
The exponential function cut the -axis at and is also decreasing because it has a decay factor, of The graph to this exponential function must be D.
The value is read to about 70 when .
The exponential function
cut the -axis at = 400 and is growing because it has a growth factor is greater than which is graph B.
The function's value looks to be approximately when .