We have been given that a a paper plane is thrown from the top of a 147-foot cliff into the water below, the height of the plane at any given time can be determined by the formula $h = -3t^2+147$ , where h is the height of the plane at t seconds.

To find the time, when plane will be at a height of exactly 20.25 feet, we will substitute $h=20.25$ in our given formula and solve for t as:

$20.25= -3t^2+147$

$-3t^2+147=20.25$

$-3t^2+147-147=20.25-147$

$-3t^2=-126.75$

$\frac{-3t^2}{-3}=\frac{-126.75}{-3}$

$t^2=42.25$

Take square root of both sides:

$t=\pm \sqrt{42.25}$

$t=\pm 6.5$

Since time cannot be negative, therefore, the plane will be at a height of exactly 20.25 feet after 6.5 seconds and option 'c' is the correct choice.

6 0

3 years ago

What’s the correct answer

Dafna11 [192]

2 number is ryt ans

6 0

3 years ago

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The y-intercept of a line is the value of the y- coordinate where the line crosses the ________

Shalnov [3]

y-axis

That last sentence though, I died reading that.

3 0

3 years ago

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