Homework Help: math

Posted by kennisha on Sunday, April 22, 2012 at 7:33pm.

the population of Canadian city is modeled by P(t)= 12t^2 + 800t + 40,00, where t is the time in years. when t=0, the year is 2007

A) according to the model, what will the population be in 2020?

B)in what year is the population predicted to be 300,000?

math - Reiny, Sunday, April 22, 2012 at 9:01pm
so for 2020 , t = 13
P(13) = 12(13)^2 + 800(13) + 40000
= .....

for the population to be 300 000
300000=12t^2 + 800t + 40000
12t^2 + 800t - -260000=0
3t^2 + 200t - 65000=0

let's use the formula
t = (-200 ą √820000)/6
= 117.6 years or a negative

totally unrealistic answer, but mathematically correct
the year would be 2007+117.6 = appr 2125

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