Math help!!

Question

A projectile is launched from ground level with an initial velocity of v 0 feet per second. Neglecting air? resistance, its height in feet t seconds after launch is given by S=-16t^2+v 0t. Find the? time(s) that the projectile will? (a) reach a height of 192 ft  and? (b) return to the ground when v 0= 112 ft per second.

 

(a) Find the? time(s) that the projectile will reach a height of 192 ft when v 0= 112 ft per second. Select the correct choice below? and, if? necessary, fill in the answer box to complete your choice.

 

A  __  seconds ?(Use a comma to separate answers as? needed.)

 

B.  The projectile does not reach 192 ft.

Answer 1

S = -16t² + V₀t

 

V₀ = 112 ft/sec

 

a) S = 192 ft.

 

                       192 = -16t² + 112t

 

   16t² - 112t + 192 = 0

 

     16 (t² - 7t + 12) = 0

 

      16 (t - 4)(t - 3) = 0

 

     t - 4 = 0    ;  t - 3 = 0

 

      t = 4 ;    t = 3

 

at 3 and 4 seconds the projectile will be 192 ft above ground