University of California, Berkeley
The Mathematics 111 Introduction to the Calculus Final Examination from Fall 2011 covered fundamental calculus concepts including limits, derivatives, integrals, and applications. Below are detailed solutions for each problem presented on the exam.
Find the limit: limx3 (x - 9)/(x - 3)
Solution:
The expression simplifies to (x+3) for all x 3, and since we're taking the limit as x approaches 3 (not evaluating at x=3), we can substitute directly.
Find the derivative of f(x) = x sin(x)
Solution:
To find the derivative, we apply both the product rule and chain rule:
Evaluate the integral: 0/2 sin(x) dx
Solution:
We use the trigonometric identity sin(x) = 1 - cos(x) to rewrite the integral:
Let u = cos(x), then du = -sin(x) dx:
Now evaluating from 0 to /2:
A water tank has the shape of an inverted circular cone with base radius 3 m and height 6 m. Water is being pumped into the tank at a rate of 5 m/min. Find the rate at which the water level is rising when the water is 2 m deep.
Solution:
Let's define our variables:
For similar triangles: r/h = 3/6, so r = h/2.
The volume of a cone is V = rh/3. Substituting r = h/2:
Differentiating with respect to time:
Solving for dh/dt:
Therefore, when the water is 2 m deep, the water level is rising at a rate of 5/ m/min.
A rectangular box with a square base and open top must have a volume of 78,088 cm. Find the dimensions of the box that minimize the amount of material used.
Solution:
Let's define our variables:
Volume constraint: V = xy = 78,088
Surface area: S = x + 4xy (base + four sides)
From volume constraint: y = 78,088/x
Substituting y into surface area equation:
To find minimum surface area, set dS/dx = 0:
Finding y:
Verifying this is a minimum: dS/dx = 2 + 624,704/x > 0 at x 53.84
Therefore, the dimensions that minimize material are: Base 53.84 cm 53.84 cm, Height 26.92 cm
Find the area of the region bounded by y = x, y = 2, and x = 0.
Solution:
First, find intersection point of y = x and y = 2:
The region is bounded by x = 0 on the left, x = 4 on the right, y = 2 on top, and y = x on the bottom.
Integrating with respect to y:
Find the derivative of F(x) = 1e sin(t) dt
Solution:
Using the Fundamental Theorem of Calculus and Chain Rule:
Therefore, the derivative of F(x) is e sin(e).
Determine whether the improper integral 1 1/x^p dx converges or diverges. For which values of p does it converge?
Solution:
Let's evaluate the improper integral:
Case 1: p = 1
The integral diverges when p = 1.
Case 2: p 1
This limit exists only when 1-p < 0, or p > 1. In this case:
Conclusion: The improper integral converges when p > 1 and diverges when p 1.
Find the Maclaurin series for f(x) = e2x.
Solution:
The Maclaurin series is the Taylor series centered at x = 0.
Derivatives of f(x) = e2x:
The Maclaurin series is:
Therefore, the Maclaurin series for e2x is n=0 (2x)/n! = 1 + 2x + 2x/2! + 2x/3! + ...
Find the intervals of concavity and the inflection points of f(x) = x - 3x + 1.
Solution:
First and second derivatives:
Possible inflection point: Set f''(x) = 0
Determine sign of f''(x) on each interval:
Since concavity changes at x = 1, we have an inflection point there.
The y-coordinate:
Conclusion:
Solve the differential equation: dy/dx = xy when y(0) = 1.
Solution:
This is a separable differential equation. Separating variables:
Integrating both sides:
Applying the initial condition y(0) = 1:
Substituting C back:
Therefore, the solution to the differential equation is y = 2/(2 - x).
