Abaseball is thrown upwards from a height of 5 feet with an initial speed of 64 feet per second, and its height h (in feet) from the ground is given by h(t) = 5 + 64t – 16t2 as shown in the graph where t is time in seconds. using a graphing calculator, at what time does the ball reach its maximum height? select one of the options below as your a. 0 b. 1 c. 2 d. 3

For this case we have the following equation:

To find the time when it reaches its maximum height, we must derive the equation.

We have then:

Then, equaling to zero and clearing the time we have:

the ball reaches its maximum height at:

C. 2

ok then what happened.

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional