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Calculus/Growth and decay problems.


Katrin wrote at 2008-03-16 22:19:20
The only problem with the answer above is when he substituted 375 for F(o) when it should be 350 instead, which will give F0=75, so your equation will be 275e^-.4t +75

I got the answer! wrote at 2008-04-06 16:32:45

step 1: set up implicit integration

dF/dt = -110e^(-.4t)

dF = -110e^(-.4t)dt

step 2: integrate both sides

F(t) = 275e^(-.4t) + C

step 3:

you've got your general equation, now transform it so that 75 deg is the horizontal asymptote

F(t) = 275e^(-.4t) + C

step 4: evaluate at t=5

F(5) = 275e^(-.4t) + C

F(5) = 112.21 degrees  

Captain wrote at 2008-04-21 05:39:56
Colleen's response has a mistake.  F(0), the starting temperature of the pizza, is 350, not 375.  This makes the constant F0 equal to 75, and your answer becomes approximately 112 degrees.

anom wrote at 2015-02-01 04:36:20
This is incorrect, the answer is 112 degrees Fahrenheit


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Paul Klarreich


All topics in first-year calculus including infinite series, max-min and related rate problems. Also trigonometry and complex numbers, theory of equations, exponential and logarithmic functions. I can also try (but not guarantee) to answer questions on Analysis -- sequences, limits, continuity.


I taught all mathematics subjects from elementary algebra to differential equations at a two-year college in New York City for 25 years.

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