Answer:
The smart-phone hit the ground when t = 7 s
Step-by-step explanation:
The height "h" is defined as:
h=16t^2 + 48t + 448
And, when the smart-phone hits the ground, h = 0 ft . Then,
16t^2 + 48t + 448 = 0
And this is a quadratic equation, and we can solve it using the formula for ax^2 + bx + c = 0, which is
x=![\frac{-b±\sqrt{b^{2}-4ac } }{2a}](https://tex.z-dn.net/?f=%5Cfrac%7B-b%C2%B1%5Csqrt%7Bb%5E%7B2%7D-4ac%20%7D%20%7D%7B2a%7D)
So,
t = ![\frac{-48±\sqrt{48^{2} -4(-16)(448)} }{2(16)}](https://tex.z-dn.net/?f=%5Cfrac%7B-48%C2%B1%5Csqrt%7B48%5E%7B2%7D%20-4%28-16%29%28448%29%7D%20%7D%7B2%2816%29%7D)
t = ![\frac{-48±\sqrt{2304+28672} }{-32}](https://tex.z-dn.net/?f=%5Cfrac%7B-48%C2%B1%5Csqrt%7B2304%2B28672%7D%20%7D%7B-32%7D)
And, we have two responses,
t_1 =
and t_2 = ![\frac{-48-\sqrt{30976} }{-32}](https://tex.z-dn.net/?f=%5Cfrac%7B-48-%5Csqrt%7B30976%7D%20%7D%7B-32%7D)
t_1 = - 4 s and t_2 = 7 s
As we know, the time is a quantity that cannot have a negative value, so, we take the result 2.
I cant answer if there is no info
0 is the answer because if it is divisible, that means that a would have to be able to go into b evenly
The answer is 6 11/12
4 1/6 = 4 2/12
2 3/4 = 2 9/12
4 2/12 + 2 9/12 = 6 11/12