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3. temperature throughout the day the temperature ( t(h) ) during a spr…

Question

  1. temperature throughout the day the temperature ( t(h) ) during a spring day can be modeled by ( t(h) = -(h - 12)^2 + 75 ), where ( t ) is the temperature in fahrenheit and ( h ) is the hour (using 24-hour time).

a. what parent function is this based on?
b. explain the meaning of each transformation
c. what is the maximum temperature and when does it occur?
d. how does this compare to ( t(h) = -h^2 + 75 )?
e. what would the new function be if the peak temperature was ( 80^circ )f?

Explanation:

Response
Part (a)

Step1: Identify Parent Function

The given function is \( T(h) = -(h - 12)^2 + 75 \). The general form of a quadratic function is \( y = ax^2+bx + c \), and the simplest quadratic function (parent function) is \( y = x^2 \). The given function is a transformed version of \( y = x^2 \) (since it has a square of a linear term in \( h \), with transformations like horizontal shift, vertical shift, and reflection).

Step1: Analyze Coefficient of Squared Term

The coefficient of \( (h - 12)^2 \) is \( - 1 \). A negative coefficient indicates a reflection over the horizontal axis (the \( h \)-axis, or in terms of the function's graph, it opens downward instead of upward like the parent function \( y = x^2 \)).

Step2: Analyze Horizontal Shift

The term \( (h - 12) \) inside the square means there is a horizontal shift. For a function \( y=(x - k)^2 \), the graph shifts \( k \) units to the right. Here, \( k = 12 \), so the graph of the parent function \( y = x^2 \) is shifted 12 units to the right (along the \( h \)-axis, which represents hours).

Step3: Analyze Vertical Shift

The \( + 75 \) at the end of the function means there is a vertical shift. For a function \( y = f(x)+k \), the graph shifts \( k \) units up. Here, \( k = 75 \), so the graph is shifted 75 units up (along the \( T \)-axis, which represents temperature in Fahrenheit).

Step1: Recall Properties of Quadratic Function

The function \( T(h)=-(h - 12)^2 + 75 \) is a quadratic function in vertex form \( y=a(x - h)^2 + k \), where \( (h,k) \) is the vertex. Since \( a=-1<0 \), the parabola opens downward, so the vertex is the maximum point.

Step2: Identify Vertex Coordinates

In the function \( T(h)=-(h - 12)^2 + 75 \), comparing with \( y=a(x - h)^2 + k \), we have \( h = 12 \) (the \( h \)-coordinate of the vertex, representing the hour) and \( k = 75 \) (the \( T \)-coordinate of the vertex, representing the temperature).

Answer:

The parent function is the quadratic function \( y = x^2 \) (or \( f(x)=x^2 \)).

Part (b)