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Expert: Sherry Wallin - 10/17/2009


Question

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i am student of mathematical economic 201 i have few question i can not solve it can you help me to show that thanks  

Answer
I can help you a little bit. I can't read the equation in part c and in part a you need to use the formula you have for present value. If you can provide me with that then I can do the math for you.
I need the result of a to do b and b to do c.(as well as being able to read the equation in c) and d.

As for the integrals the first one can be done as follows:
Let ln(y) = u so that du = 1/y dy, now put that in the integral as int(u du)and you need to change the limits of integration for using the variable u. So when y =1 then ln 1 = 0 and when y = e the lne = 1 so your new limits of integration are [0,1]. Now you are integrating u du with limits [0,1]. The result is u^2/2 evaluated at 1 is 1/2 and evaluated at 0 is o so the answer is 1/2


the 2nd one can be done as follows:
let e^(2/x)be e^u where u = 2x^-1 = 2/x so du = -2x^-2 dx -> (-1/2)du = 1/x^2 dx. So you are integrating the int((-1/2)e^u du) which is just (-1/2)e^u = (-1/2)e^(2/x). You can check this by taking the derivative of the result and seeing you get what you want to integrate.

I'll have to think about how to do the third integral. It may need a table of integrals, let me see if I can come up with an answer for that one.

Math Prof

Sherry Wallin

Expertise

I can answer most questions up through Calculus and some in Number Theory and Abstract Algebra.

Experience

I have had my Bachelor's Degree since 1987 and have been a teacher since 1988. I earned my Masters Degree in Mathematics May 2010. I have been teaching at the same community college since 2002.

Education/Credentials
I have taught 12 years at the community college level, medical college, and technical college as well as a high school instructor and alternative education instructor and charter school instructor.

Awards and Honors
Master's GPA 3.56 Bachelor's GPA 3.34 Post grad work not degree related GPA 4.0

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