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MAT137: Calculus with proofs
Test 1
Full Name:
Student Number:
Instructions
• Write clearly and concisely in a linear fashion.
• Explain all your steps. Unless stated otherwise, show all of your work. You must give all the details of
how to solve the problem by hand.
• How to submit your answers. You may use either of the following three methods.
1. Write digitally: using a tablet or digital pen to write directly onto the pdf
2. Print + Scan: printing the pages, writing your responses into the appropriate places using a pen or
pencil, and scanning them.
3. Write on blank paper + Scan: writing your answers on blank/lined paper, then scanning them. Please
indicate clearly which page corresponds to which question. When uploading your answers to Gradescope,
match your answers to the appropriate questions.
You may use a scanner or a smartphone scanner app (such as Scannable by Evernote).
• The test starts at 6pm ET. You have until 8pm ET to submit your responses on Gradescope.
There are 7 questions, for a total of 50 points.
Page 1 of 11
1. Consider the following statement:
“For every differentiable function f on R, if f is increasing on [a, b], then ∀x ∈ (a, b), f ′(x) > 0.”
(a) (2 points) In words and symbols, write the negation of this statement without using “no”,“not”,
“none”, “¬”, etc.
.
(b) (4 points) If the original statement is true, then prove it. If the statement is false, then prove
its negation.
Page 2 of 11
2. (8 points) Prove directly from the definitions of the derivative and of the limit that if f(x) =
3
x− 2,
then f ′(1) = −3. Note that this is an ε-δ proof, so you are not allowed to use limit or differentiation
rules.
Page 3 of 11
3. Compute the following limits using any method that you want. Show all of your work.
(a) (4 points)
lim
x→1
x2 + 4x− 5√
x− 1
Page 4 of 11
(b) (4 points)
lim
x→0
sin(7 tan(3x))
tan(4 sin(5x))
Page 5 of 11
(c) (4 points)
lim
x→0+
(x+ ex)
1
x
Page 6 of 11
4. Let f(x) = x3 + 6x2 − 36x+ 5.
(a) (3 points) What is the largest interval containing 0 on which f is one-to-one? Write the interval
below. No justification is needed.
The interval is .
(b) (3 points) Let g be the inverse of f on the interval of the previous part. What is g′(5)? No
justification is needed
g′(5) = .
Page 7 of 11
5. (5 points) Find the equation of the line tangent to the curve x2+y3 = x3+y at (1, 1). No justification
is needed.
The equation of the tangent line is .
Page 8 of 11
6. Let f be a differentiable function on R. The table below lists the values of f at 6 different points.
x -2 -1 0 1 2 3
f(x) 3 3 -1 0 2 -2
(a) (2 points) What is the smallest number of zeros that f must have? No justification is needed.
The function f must have at least zero(s).
(b) (2 points) What is the smallest number of zeroes that f ′ must have? No justification is needed.
The function f ′ must have at least zero(s).
Page 9 of 11
7. Let f be a continuous function on [0, 14]. The graph of its derivative is sketched below.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
−4
−3
−2
−1
0
1
2
3
4
f ′(x)
(a) (3 points) Find all the local maxima of f . Don’t forget to include endpoints as potential local
maxima. No justification is needed.
The local maxima of f are located at x = .
(b) (3 points) Find all the local minima of f . Don’t forget to include endpoints as potential local
minima. No justification is needed
The local minima of f are located at x = .
(c) (3 points) Find all the inflection points of f . No justification is needed.
The inflection point(s) of f are located at x = .