3) A rock is thrown off the top of an 80-foot building. The function f(t) = -16+2 +64t + 80 represents the height of the rock and trepresents the time in seconds after the rock is thrown.

How long is the rock in the air?

What is the maximum height achieved by the rock?

How high is the rock after 3.7 seconds?

What is a reasonable domain for this situation?

What is a reasonable range?

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!

answer:

at time x=0 we have 1000, at time x=1 we have 2000, at time x=2 we have 4000.  

so that's an initial value of 1000 and a ratio of 2,

y = 1000 (2^x)

hope this !