Word problem = stuck me. Help?

heatherjoy

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(Note: I don't understand how to begin, nor do I understand any of the rest of it. In need of step-by-step elaboration.)

Thanks in advance!
H

A canon on the top of a cliff is fired at a target in a valley 561 ft below. The height of the cannonball above the floor of the valley can be modeled by the equation: H(t)= -16t^2+554t+561 ,where H is the height of the cannonball above the floor of the valley, and t is the time in seconds after the cannonball is fired. How many seconds after the cannonball is fired will it be at its highest point? Round your final answer to thousandths of a second.
 
Dear frnd

I will suggest u to make derivative of h with respect to t. Then solve t frm the equation that u hav frm derivation. U will get two answer .one is at the maximum point of the cnon ball and the other is at the minimum point.
 
I will suggest [you] to make derivative of h with respect to t.

Hi chandra:

A calculus approach is not appropriate for a beginning algebra student.

By the way, the symbol for the dependent variable is H, not h.

Cheers :)
 
I don't understand how to begin, nor do I understand any of the rest of it.

H(t)= -16t^2 + 554t + 561

where H is the height of the cannonball above the floor of the valley, and t is the time in seconds after the cannonball is fired

How many seconds after the cannonball is fired will it be at its highest point? Round your final answer to thousandths of a second.


Hi Heather:

The given formula for H is quadratic, in the form At^2 + Bt + C. I hope that you've studied quadratic equations.

You should know that the graph of H is a parabola that opens downward (because the leading coefficient is negative); therefore, the highest point on the graph is the vertex.

The question asks for the t-coordinate of the vertex point.

There is a simple formula (which you need to memorize) for the horizontal coordinate of any upward- or downward-opening parabola's vertex. The formula is stated in terms of the quadratic's first two coefficients.

t = -B/(2A)

Substitute the known values for A and B into this formula and simplify.

Round the result to the nearest thousandth.

Please show your work, if you would like more help. Otherwise, post your answer, and we'll check it.

Cheers :)
 
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