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Papessa [141]
3 years ago
11

Daniel dives into a swimming pool. The height of his head is represented by the function h(t) = -8t2 - 28t + 60, where t is the

time in seconds and h(t) is the height of his head, in inches.
How many seconds will it take for Daniel's head to reach the surface of the pool?
Mathematics
1 answer:
8_murik_8 [283]3 years ago
6 0
So, h(t) is how far is Daniel's head from the surface of the water, namely the surface itself is when the height is nill, so his head is at the surface and the height of it is just 0, thus h(t)  = 0.  Namely, what is "t" when h(t) is 0?

\bf h(t)=-8t^2-28t+60\implies \stackrel{h(t)}{0}=-8t^2-28t+60
\\\\\\
0=-2t^2-7t+15\implies 2t^2+7t-15=0\implies (2t+3)(t-5)=0
\\\\\\
\begin{cases}
2t+3=0\implies 2t=-3\implies &t=-\frac{3}{2}\\\\
t-5=0\implies &\boxed{t=5}
\end{cases}

clearly the seconds cannot be a negative unit, so is not -3/2.
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Answer:

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Step-by-step explanation:

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3 years ago
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5 0
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Step-by-step explanation:

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