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PLEASEEEE HELPPPPP A flying disk is thrown into the air from a height of 25 feet at time t=0. The function that models this situation is h(t) = -16t2 + 75t + 25, where t is measured in seconds and h is the height in feet. Which values best describe the domain of the function in the context of the problem?
A. 0 ≤ t ≤ 5
B. 0 ≤ t ≤ 25
C. All real numbers
D. All positive integers

Respuesta :

Answer:

A)

Step-by-step explanation:

Given function:  

[tex]h(t)=-16t^2+75t+25[/tex]

The domain (input values) will be the x-intercepts, so the values of t when h(t) = 0.

The quickest way to find these is to use the quadratic formula.

Quadratic Formula

[tex]x=\dfrac{-b \pm \sqrt{b^2-4ac} }{2a}\quad\textsf{when}\:ax^2+bx+c=0[/tex]

[tex]\implies t=\dfrac{-75 \pm \sqrt{75^2-4(-16)(25)} }{2(-16)}[/tex]

[tex]\implies t=\dfrac{-75 \pm \sqrt{7225}}{-32}[/tex]

[tex]\implies t=\dfrac{75 \pm 85}{32}[/tex]

[tex]\implies t=5, t=-\dfrac{5}{16}[/tex]

Time cannot be negative.

When h(t) = 0, the disk will hit the floor.

Therefore, the domain is restricted to 0 ≤ t ≤ 5