Question an-eng

2.1 Nonlinear Functions - Quadratic graphs and vertex form
0:00

f of theta equals, negative 0 point 2 8, times, open parenthesis, theta minus 27, close parenthesis, squared, plus 880

An engineer wanted to identify the best angle for a cooling fan in an engine in order to get the greatest airflow. The engineer discovered that the function above models the airflow f of theta, in cubic feet per minute, as a function of the angle of the fan theta, in degrees. According to the model, what angle, in degrees, gives the greatest airflow?

A.

–0.28

B.

0.28

C.

27

D.

880

An engineer wanted to identify the best angle for a cooling fan in an engine in

Hard-difficulty · SAT Math · Nonlinear Functions — Quadratic graphs and vertex form. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice C is correct. The function f is quadratic, so it will have either a maximum or a minimum at the vertex of the graph. Since the coefficient of the quadratic term (–0.28) is negative, the vertex will be at a maximum. The equation f(theta) = –0.28(theta – 27)2 + 880 is given in vertex form, so the vertex is at theta = 27. Therefore, an angle of 27 degrees gives the greatest airflow.

Choices A and B are incorrect and may be the result of misidentifying which value in a quadratic equation in vertex form represents the vertex. Choice D is incorrect. This choice identifies the maximum value of f(theta) rather than the value of theta for which f(theta) is maximized.