Answer :
Answer:
9° Celsius
Step-by-step explanation:
Given,
The heated piece of metal cools according to the function,
[tex]C(x)=(0.5)^{x-9}[/tex]
After adding the device that cools according the function,
[tex]h(x)=-x-2[/tex]
The new function that shows the final temperature of the metal,
[tex]f(x)=C(x)+h(x)[/tex] ( Let )
[tex]=(0.5)^{x-9}-x-2[/tex]
Hence, the temperature of the metal after five hours would be,
[tex]f(3) = (0.5)^{5-9}-5-2 =0.5^{-4}-7=(\frac{1}{2})^{-4}-7=2^4-7=16-7=9^{\circ}\text{ Celsius}[/tex]
Third Option is correct.