Intermediate Algebra – Student Workbook – Second Edition 2013

Lesson 3a – Introduction to Exponential Functions
Mini-Lesson
Press 2 nd >CALC
Scroll to 5: INTERSECT and press ENTER
Notice the question, “First Curve?” The calculator is
asking if
Y1 = 125(1.25) x is the first curve in the intersection.
Press Enter to indicate “Yes”
Notice the question, “Second Curve?” The calculator is
asking if
Y2 = 300 is the second curve in the intersection.
Press Enter to indicate “Yes”
Press Enter at the “Guess” question and obtain the
screen at right. Your intersection values are given
at screen bottom and the intersection is marked
with a cursor. Round as indicated in your problem
directions or as dictated by the situation.
For this problem, we were asked to find x when f(x) = 300. Round to two decimal places. Our
response is that, “When f(x) = 300, x = 3.92”. Note that this information corresponds to the
ordered pair (3.92, 300) on the graph of f(x) = 125(1.25) x
Problem 11
YOU TRY – GIVEN OUTPUT FIND INPUT
Given g(x) = 125(0.75) x , find x when g(x) = 300 (to two decimal places) using the same process
as above.
a) What equation will you solve to respond to the given question? __________________
b) On your calculator, you will let Y1 = ________________ and Y2 = _______________
c) What values are you using for your WINDOW: xmin=____, xmax=_____, ymin=____,
ymax=____
d) What is the value of x that you found when g(x) = 300? _________________________
(using 5: INTERSECT)
e) To what ordered pair does this information correspond? _______________
f) Include a rough but accurate sketch of the graphs and
intersection in the box to the right. Mark and label the
intersection.
Scottsdale Community College Page 107 Intermediate Algebra