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chwala

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**1.**Homework Statement

A tree is planted as a seedling of negligible height. The rate of increase of its height , in metres per year is given by ##0.2√(25-h)##

a. explain why tree can't exceed 25 metres. answer⇒

##dh/dt=0## when h=25

b. express t as a function of h answer⇒ ##t=-10√(25-h)+50##

c. how long does it take for tree to put on

**(i) its first metre**

**(ii)its last metre**

d. express h as a function of t here i did it like this ##h=25-(t^2-100t+2500/100)##

##h=2500-t^2+100t-2500/100##

##h= -t^2+100t/100##

##h=t-0.01t^2## which agrees with textbook answer. where ##0≤t≤50##

## Homework Equations

## The Attempt at a Solution

c(i)##t=-10√25-1+50 t=1.0## years , this is the correct answer as per textbook.

c(ii) solution is ##t=10## years implying that h=9

my question is why ##h=9##?why not 15 or 20? i was unable to solve c(ii)[/B]

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