11-17 Class notes Graphs of Exponential Growth and Decay

Use a graphing calculator to enter the sequences

y1=   6  (  1.2  )  ^  X     and

y2=   6  (  0.9  )  ^  X

TRACE

The y1 graph of an exponential growth curve increases because b, the growth factor, is 1.2 > 1.

The y2 graph of an exponential decay curve decreases because b, the growth factor, is 0.9 < 1.


The general form of an exponential growth function is y = a*b^n  where a is the initial value and b is the growth factor, b > 1 and b can not equal 1.

The general form of an exponential decay function is y = a*b^n  where a is the initial value and b is the decay factor, b < 1 and b can not equal 1.

The exponent X is how many times we use the growth or decay factor to multiply the initial value.

The domain of the exponential growth and decay functions is x = all real numbers

The range is y > 0.


Homework for 11-22 is page 108, Check Understanding, problems 1, 2, 3.
Shrinking Violets.  Hint - the decay factor is 0.8.