Econ 302: Practice
Questions 1
The following questions are a calculus review. If you master them
then the level of calculus used in the class should not
be a problem for you.
If you feel you need more practice, check the the following questions.
If you just need a little bit of help click
here for a short calculus review.
Question 1: Compute the first derivative of the
following functions
- f(x)=x2/(1+4x)
- f(x)=ln(x+20) (recall that the derivative of ln(x) is
1/x).
- f(x)=ln(x+a) where a is a fixed number.
Note that if you choose a=20 the answer of both this question and
the previous one must be the same.
- f(x)=(4+x4)1/2
Note that (...)1/2 is the same as the square root of
(...).
- f(x)=(a+x4)1/2 where a is a
fixed number.
Choose a=4 to check your answer.
- f(x)=3x2+6x4.
- f(x)=ax2+bx4 where a and
b are fixed numbers.
Choose a=3 and b=6
to check your answer.
Question 2: Compute the partial derivatives with
respect to x and y for the functions listed below.
Note that if you take a partial derivative of a function with respect
to one variable then you treat all other variable as if they were
fixed numbers (i.e., in the questions above with
numbers a or b you have essentially already taken a
partial derivative).
- f(x,y)=xy3
- f(x,y)=x+20y
- f(x,y)=10ln(x)+ln(y).
- f(x,y)=(x+2y)/y.
- f(x,y)=2x2+y.
- f(x,y)=ax2+by where a and
b are fixed numbers.
Again, check your answer for a=2 and b=1
Question 3: The following exercises will be useful for graphing indifference curves.
- Assume that x2y=20.
- Write y as a function of x.
- Graph the function for x>=0, where x is graphed on the horizontal axis, and y on the vertical axis.
- Determine the slope at x=2.
- Determine the value of y at x=2.
-
Now assume that the function is given by xy2=36.
- Again write y as a function of x.
- Graph the function for x>=0, where x is graphed on the horizontal axis, and y on the vertical axis.
- Determine the slope at x=4.
- Determine the value of y at x=4.
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