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A patient has an illness that typically lasts about 24 hours. The temperature, [tex]T[/tex], in degrees Fahrenheit, of the patient [tex]t[/tex] hours after the illness begins is given by:

[tex]\[ T(t) = -0.012t^2 + 0.288t + 97.1 \][/tex]

Use your calculator to graph the function and answer the following questions. Round all answers to 1 decimal place.

1. When does the patient's temperature reach its maximum value?
Answer: [tex]$\square$[/tex]

2. What is the patient's maximum temperature during the illness?
Answer: [tex]$\square$[/tex]


Sagot :

To solve this problem, let's analyze the given temperature function:

[tex]\[ T(t) = -0.012 t^2 + 0.288 t + 97.1 \][/tex]

This is a quadratic function of the form [tex]\( T(t) = at^2 + bt + c \)[/tex], where:
- [tex]\( a = -0.012 \)[/tex]
- [tex]\( b = 0.288 \)[/tex]
- [tex]\( c = 97.1 \)[/tex]

For a quadratic function [tex]\( ax^2 + bx + c \)[/tex], the maximum or minimum value (vertex) occurs at [tex]\( t = -\frac{b}{2a} \)[/tex]. Since the coefficient of [tex]\( t^2 \)[/tex] (i.e., [tex]\( a \)[/tex]) is negative, this quadratic function opens downwards and thus has a maximum value.

To find the time [tex]\( t \)[/tex] at which the maximum temperature occurs, we use:

[tex]\[ t = -\frac{b}{2a} \][/tex]

Substituting the given values of [tex]\( a \)[/tex] and [tex]\( b \)[/tex]:

[tex]\[ t = -\frac{0.288}{2(-0.012)} \][/tex]

Further simplifying, we get:

[tex]\[ t = -\frac{0.288}{-0.024} = 12.0 \][/tex]

This means the patient's temperature reaches its maximum value at [tex]\( t = 12.0 \)[/tex] hours after the illness begins.

Next, to find the maximum temperature, we substitute [tex]\( t = 12.0 \)[/tex] back into the original function:

[tex]\[ T(12.0) = -0.012 (12.0)^2 + 0.288 (12.0) + 97.1 \][/tex]

Calculating each term individually:

[tex]\[ -0.012 \times 144 + 0.288 \times 12 + 97.1 = -1.728 + 3.456 + 97.1 \][/tex]

Summing these values gives:

[tex]\[ -1.728 + 3.456 = 1.728 \][/tex]
[tex]\[ 1.728 + 97.1 = 98.8 \][/tex]

Thus, the maximum temperature the patient reaches during the illness is [tex]\( 98.8 \)[/tex] degrees Fahrenheit.

So, summarizing our answers:

1. The patient's temperature reaches its maximum value after [tex]\( 12.0 \)[/tex] hours.
2. The maximum temperature during the illness is [tex]\( 98.8 \)[/tex] degrees Fahrenheit.