Answer:
2
Step-by-step explanation:
The height formula given is:
h = -16t^2 + 70
That means the object will be initially (t=0) at the height 70 feet, from where it will be dropped.
If we want to know the time when the object will be at height 6 feet, we just need to use h=6 in the equation, and then calculate the value of t:
6 = -16t^2 + 70
16t^2 = 64
t^2 =4
t = 2 s
So, it will take 2 seconds for the object to be 6 feet above the valley floor.
Answer:
40 minutes
Step-by-step explanation:
Let c represent the number of minutes it would take colleen to finish the job when he is working alone. Hence, it can be represented by the equation:

Solving the quadratic equation to get c gives:
c = -12 and c = 40
Since the time cannot be negative, hence c = 40 minutes.
It would take colleen 40 minutes to clear the yard of leaves alone
4 3/4 - 4 1/3
= 4 9/12 - 4 4/12
= 5/12 <==== extra cup put in