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anonymous
 5 years ago
a rocket is fired into the air from the top a building. The equation H= 16t2 + 96t + 120 gives H, the height of the rocket in feet, t seconds after it was fired.
a) How tall was the building?
b) What was the maximum height of the rocket?
c) When did the rocket hit the ground?
anonymous
 5 years ago
a rocket is fired into the air from the top a building. The equation H= 16t2 + 96t + 120 gives H, the height of the rocket in feet, t seconds after it was fired. a) How tall was the building? b) What was the maximum height of the rocket? c) When did the rocket hit the ground?

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anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0a) substitue t=0 into the equation. b) dH/dt = 0

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0a. well when time = 0 the rocket has not fired yet and it is sitting on top of the building so H = 16(0) + 96(0) + 120

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Are you in Algebra or Calculus?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0c) let H =0, the solve the quadratic equation

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0OK. so we need to find the maximum of the parabola. It is found when x = b/2a (x in this case is t) so t = 96/32 which is t = 3 that means when t = 3 or after 3 seconds, it is at its highest point. to find out how high that point is put in 3 for t H = 16(3^2) + 96(3) + 120

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0To find out when it hits the ground, we need to find out when H = 0 0 = 16t^2 + 96t + 120 we need to factor this or use the quadratic formula. which do you want to do?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0OK.. you always want the t^2 to be positive so we are going to take it over to the other side of the equation

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.016t^2  96t  120 = 0 OK?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.08(2t^2  12t  15) factor out the GCF which is 8

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Well... it doesn't factor so we have to use the quadratic formula. I am going back to the original 16t^2  96t  120 = 0

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0x = b + sqrt(b^2  4ac)  2a

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0x = 96 + sqrt((96)^2  4(16)(12))  2(16)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0x = 96 + sqrt(9216 + 768)  32

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0x = 96 + sqrt(9984)  32

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0x = 96 + 99.92  32 x = .1225 or x = 6.1225 since x represents seconds then it would be on the ground at 6.1 seconds
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