## exponential word problem

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
sully039
Posts: 16
Joined: Mon Jul 25, 2011 8:33 pm
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### exponential word problem

The Mckinney family has a pond in their yard with water lillies. The area of the lilies' leaves cover twice as much of the pond as they did 35 days ago. The leaves will completely cover the pond in 80 days if they continue to grow unchecked. The McKinneys want to cut back the lilies when they have covered at most half the area of the pond. When is this growth expected to happen?

I don't really understand how to set up this problem. Could someone help?
Btw the answer is 45 days. I just don't know how they got this lol

little_dragon
Posts: 226
Joined: Mon Dec 08, 2008 5:18 pm
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### Re: exponential word problem

The area of the lilies' leaves cover twice as much of the pond as they did 35 days ago.
so wats the half-life?
The leaves will completely cover the pond in 80 days
go backwrds from the half-life to get when half is covered

sully039
Posts: 16
Joined: Mon Jul 25, 2011 8:33 pm
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### Re: exponential word problem

So you mean to use the half life equation like this? :y=c(1/2)35/h
2c=c(1/2)35/h
But when I do this, half life is equal to -35...

little_dragon
Posts: 226
Joined: Mon Dec 08, 2008 5:18 pm
Contact:

### Re: exponential word problem

So you mean to use the half life equation like this? :y=c(1/2)35/h
2c=c(1/2)35/h
no
wats the half-life in days?
U double going forward & half going backwards
starting @ 80 days (full) when do U have half full?