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This Lesson (Writing a function rule for a function based on its wording description) was created by by ikleyn(52780)  : View Source, ShowAbout ikleyn:
Writing a function rule for a function based on its wording description
Problem 1The functions f(x) and g(x) are sine functions, where f(0) = g(0) = 0.
The amplitude of f(x) is twice the amplitude of g(x).
The period of f(x) is one-half the period of g(x).
If g(x) has a period of and = 4, write the function rule for g(x).
Solution
According to the problem, functions g(x) is sinusoidal, has the value of 0 at x= 0
and has a period . Hence, g(x) has the form
g(x) = , where real number "b" is the amplitude of g(x).
Function f(x) is sinusoidal, has the value of 0 at x= 0 and has a period, which is
one-half of that of g(x), i.e. . Hence, f(x) has the form
f(x) = , where real number "a" is the amplitude of f(x).
Next, we are given = 4. It means = 4, or = 4.
Since = 1, it gives us a = 4.
It implies, due to the problem description, that the amplitude of g(x) is 2 : b = 2.
Thus g(x) has the form
g(x) = . ANSWER
My other lessons in this site on plotting and analyzing functions are
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- HOW TO PLOT transformed functions
- HOW TO write functions for transformed plots
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Use this file/link ALGEBRA-I - YOUR ONLINE TEXTBOOK to navigate over all topics and lessons of the online textbook ALGEBRA-I.
Use this file/link ALGEBRA-II - YOUR ONLINE TEXTBOOK to navigate over all topics and lessons of the online textbook ALGEBRA-II.
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