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Stuck on this. 60 points!

Stuck on this. 60 points!-example-1
User Treffer
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2 Answers

2 votes

Answer:

Statement 1 and 2

Explanation:

If you take t^2 - 16t + 55 and find some of its graphical values, you will get:

Turning point: (8,-9)

Roots: (5,0) and (11,0)

When this graph is plotted and you imagine the x axis to be time (as stated in the question), each of the roots (x - intercept) must be when the swimmer goes under and when they come back up.

This means that the swimmer dived under the water at 5 seconds and came back up at 9, making the first 2 statements correct.

Now the fourth statement is ruled out.

The fifth statement is not plausible as the graph would have to have more than 2 roots for the swimmer to enter the water twice.

That leaves the third statement. If you imagine the depth of the swimmer to be the y axis of our imaginary graph, and we know that the y axis of the turning point is -9, that means that the swimmer's deepest dive was 9 feet under the water, ruling out the third statement too.

Hope this helps :D

User Wajdy Essam
by
7.4k points
2 votes

Answer:


h(t)= (t-5)(t-11)

The swimmer comes back up 11 seconds after the timer is started.

The swimmer dives into the water 5 seconds after the timer is started.

Explanation:

Given function:


h(t)=t^2-16t+55

To factor a quadratic in the form
ax^2+bx+c,

find two numbers that multiply to
ac and sum to
b:


\implies ac=55


\implies b=-16

Two numbers that multiply to 55 and sum to -16 are: -11 and -5

Rewrite b as the sum of these two numbers:


\implies t^2-11t-5t+55

Factorize the first two terms and the last two terms separately:


\implies t(t-11)-5(t-11)

Factor out the common term (t - 11):


\implies (t-5)(t-11)

Therefore, the given formula in factored form is:


h(t)= (t-5)(t-11)

The swimmer's depth is modeled as h(t). Therefore, when h(t) = 0 the swimmer will be at the surface of the water.


\implies h(t)=0


\implies (t-5)(t-11)=0


\implies t-5=0\implies t=5


\implies t-11=0 \implies t=11

Therefore, the swimmer will be at the surface of the water at 5 s and 11 s.

The swimmer's maximum depth is the vertex of the function. The x-value of the vertex is the midpoint of the zeros. Therefore, the x-value of the vertex is t = 8.

Substitute t = 8 into the function to find the maximum depth:


\implies h(8)=8^2-16(8)+55=-9

So the swimmer's maximum depth is 9 ft.

True Statements

The swimmer comes back up 11 seconds after the timer is started.

The swimmer dives into the water 5 seconds after the timer is started.

User Shawnic Hedgehog
by
7.8k points

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