The growth rate for the dwarf juniper plant t years after planting is approximated by the function:
dh = 17.6 t inches per year
dt √17.6t²+1
If a juniper seeding is 4 inches tall when first planted, find a function h(t)=height of the plant after t years.
What is the height of the plant after 5 years???
The growth rate for the dwarf juniper plant t years after planting is approximated by the function:?
I'm assuming
(dh/dt) = (17.6t) / (17.6 t^2 + 1)
Integrating this gives
h = sqrt (17.6 t^2 + 1) + c
Plugging in h(0) = 4 gives c = 3
h(5) = sqrt (17.6(25) + 1) + 3
Answer: h(5) = 24 inches
Reply:after 5 years :
4 inch + integral 17.6 t / √17.6t²+1 dt : between t=0 and t=5
.
integral 17.6 t / √17.6t²+1 dt = sqrt(17.6t^2 + 1)
.now its only a matter of filling in the numbers.
Reply:That's an easy one to integrate
If you don't know how, use the substitution
u = 17.6t^2 + 1
h - h0 = sqrt(17.6t^2 + 1) - 1
I played around with the initial conditions there.
You may be more comfortable writing it in the form
h = sqrt(17.6t^2 + 1) + c
Anyway, when t = 5
h - 4 = sqrt(441) - 1 = 20
h = 24 inches = 2 feet
Reply:dh/dt = 17.6t/(sqrt(17.6t^2 + 1))
= 17.6t(17.6t^2 + 1)^(-1/2)
Integrate dh/dt with respect to t by letting U = (17.6t^2 + 1)
and du = 2*17.6t
I get h(t) = (17.6t^2 + 1)^(1/2) + C
Put in h(0) = (17.6*0^2 + 1)^(1/2) + C and get C = 3.
So, h(5) = (17.6*5^2 + 1)^(1/2) + 3 = (17.6*25 + 1)^(1/2) + 3
or Sqrt(450) + 3 = 3*Sqrt(10) + 3.
arenas
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