BB2 math question help

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1

<p>h(t)= c-(d-4t)^2</p>

<p>At time t=0, a ball was thrown upward from an initial height of 6 ft. Until the ball hit the ground, its height, in feet, after t seconds was given by the function h above, in which c and d are positive constants. If the ball reached its max. height of 106 ft. at time t= 2.5., what was the height, in ft., of teh ball at time t=1.</p>

<p>According to the answer key,the correct answer is 70. How did they get 70?</p>

2

<p>System of equations.</p>

<p>They give you that:
(1) h(0) = 6
(2) h(2.5) = 106</p>

<p>h(0) = 6 = c - d^2
h(2.5) = c - (d - 10)^2
= c - d^2 + 20d - 100</p>

<p>At this point, we can subsitute 6=c - d^2 into the 2nd eqn:</p>

<p>106 = 6 + 20d - 100
d=10</p>

<p>Therefore:
c=106</p>

<p>And:
h(1)=106 - (10 - 4)^2
h(1)=70</p>

3

<p>Got it, thanks!!</p>