
AP Calculus BC Scoring Guide
Unit 7 Progress Check: FRQ Part A
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1.
NO CALCULATOR IS ALLOWED FOR THIS QUESTION.
Show all of your work, even though the question may not explicitly remind you to do so. Clearly
label any functions, graphs, tables, or other objects that you use. Justifications require that you
give mathematical reasons, and that you verify the needed conditions under which relevant
theorems, properties, definitions, or tests are applied. Your work will be scored on the
correctness and completeness of your methods as well as your answers. Answers without
supporting work will usually not receive credit.
Unless otherwise specified, answers (numeric or algebraic) need not be simplified. If your
answer is given as a decimal approximation, it should be correct to three places after the
decimal point.
Unless otherwise specified, the domain of a function is assumed to be the set of all real
numbers for which is a real number.
The population of a virus in a host can be modeled by the function that satisfies the
differential equation , where is measured in millions of virus cells and is
measured in days for . At time days, there are 10 million cells of the virus in
the host.
(a) Write an equation for the line tangent to the graph of at . Use the tangent line to
approximate the number of virus cells in the host, in millions, at time days.
Please respond on separate paper, following directions from your teacher.
(b) Show that satisfies the differential equation
with initial condition .
Please respond on separate paper, following directions from your teacher.
(c) The host receives an antiviral medication. The amount of medication in the host is
modeled by the function that satisfies the differential equation , where is