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December 20, 2014

December 20, 2014

Posted by **Nisabel** on Friday, March 28, 2014 at 10:09pm.

reaches maximum height of 8.25 feet after 1.25 seconds.

reaches a maximum height of 8.25 feet after 0.63 seconds

reaches a maximum height of 0.16 feet after 1.34 seconds

reaches a maximum height of 0.32 feet after 1.34 seconds

- math -
**Damon**, Friday, March 28, 2014 at 10:37pmassume no calculus allowed

thus complete he square to find the vertex of this parabola

16 t^2 - 20 t - 2 = -h

16 t^2 -20 t = - h + 2

t^2 - 5/4 t = - h/16 + 1/8

t^2- 5/4 t+ 25/64 = -h/16 + 8/64 + 25/64

(t - 5/8)^2 = -(1/16)(h - 33/4)

so in 5/8 of a second it reaches the vertex at 33/4 = 8 1/4 ft

- math -
**Bosnian**, Friday, March 28, 2014 at 10:41pmh ( t ) = a t ^ 2 + b t + c

h ( t ) = – 16 t ^ 2 + 20 t + 2

a = - 16

b = 20

c = 2

t - coordinate of minimum point

t = - b / 2 a

t = - 20 / [ 2 * - 16 ) ]

t = - 20 / - 32 = 20 / 32 = 4 * 5 / ( 4 * 8 ) = 5 / 8 = 0.625

h - coordinate of minimum point

h = - ( b ^ 2 - 4 a c ) / 4 a

h = - [ 20 ^ 2 - 4 * ( - 16 ) * 2 ] / [ 4 * ( - 16 ) ]

h = - ( 400 + 128 ) / - 64 = - 528 / - 64 = 528 / 64 = 16 * 33 / ( 16 * 4 ) = 33 / 4 = 8.25

Round to the nearest hundredth:

t = 0.63 , h = 8.25

- math -
**Nisabel**, Friday, March 28, 2014 at 10:46pmThank you omygosh you guys saved me!

- math -
**Damon**, Friday, March 28, 2014 at 11:16pmYou are welcome:)

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