Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Calculus II: Practice Problems Answers, Exams of Calculus

Answers to practice problems in calculus ii, including solving for x, finding derivatives, integrals, and solving initial value problems. Topics covered include logarithmic functions, exponential functions, and differential equations.

Typology: Exams

2021/2022

Uploaded on 02/24/2022

anandamayi
anandamayi ๐Ÿ‡บ๐Ÿ‡ธ

4.2

(9)

250 documents

1 / 3

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Calculus II
Practice Problems 1: Answers
1. Solve for x:
a) 6x
๎˜€
362
๎˜
x
Answer. Since 36
๎˜€
62, the equation becomes 6x
๎˜€
62
๎˜‚
2
๎˜
x
๎˜ƒ
, so we must have x
๎˜€
2
๎˜„
2
๎˜…
x
๎˜†
which has the
solution x
๎˜€
4
๎˜‡
3.
b) ln3x
๎˜€
5
Answer. If we exponentiate both sides we get x
๎˜€
35
๎˜€
243.
c) ln2
๎˜„
x
๎˜ˆ
1
๎˜†๎˜‰๎˜…
ln2
๎˜„
x
๎˜…
1
๎˜†
๎˜€
ln28
Answer. Since the difference of logarithms is the logarithm of the quotient, we rewrite this as
ln2
๎˜„
x
๎˜ˆ
1
x
๎˜…
1
๎˜†
๎˜€
ln28
๎˜Š
which is, after exponentiating, the same as x
๎˜ˆ
1
x
๎˜…
1
๎˜€
8
๎˜Š
which gives us x
๎˜ˆ
1
๎˜€
8
๎˜„
x
๎˜…
1
๎˜†
, so that x
๎˜€
9
๎˜‡
7.
2. Find the derivative of the given function:
a) y
๎˜€
ln
๎˜„
lnx
๎˜†
Answer. Use the chain rule: dy
dx
๎˜€
1
lnx
d
dx lnx
๎˜€
1
xlnx
b) y
๎˜€
log2
๎˜„
x2
๎˜ˆ
1
๎˜†
Answer. Remember that log2A
๎˜€
lnA
๎˜‡
ln2, so y
๎˜€
๎˜„
ln
๎˜„
x2
๎˜ˆ
1
๎˜†๎˜‹๎˜†๎˜Œ๎˜‡
ln2. Then, use the chain rule:
dy
dx
๎˜€
1
๎˜„
ln2
๎˜†๎˜๎˜„
x2
๎˜ˆ
1
๎˜†
2x
๎˜€
2
ln2
x
x2
๎˜ˆ
1
๎˜Ž
c) y
๎˜€
ex2
x
Answer. Use the quotient rule carefully:
dy
dx
๎˜€
x
๎˜„
2xex2
๎˜†๎˜‰๎˜…
ex2
x2
๎˜€
2ex2
๎˜…
x
๎˜
2ex2
๎˜Ž
๎˜€
ex2
๎˜„
2
๎˜…
x
๎˜
2
๎˜†
pf3

Partial preview of the text

Download Calculus II: Practice Problems Answers and more Exams Calculus in PDF only on Docsity!

Calculus II Practice Problems 1: Answers

  1. Solve for x :

a) 6 x^^ 362  x

Answer. Since 36 62 , the equation becomes 6 x^^ 62

 2  x 

, so we must have x 2  2  x  which has the

solution x 4 3.

b) ln 3 x 5

Answer. If we exponentiate both sides we get x 35 243.

c) ln 2  x  1  ln 2  x  1  ln 2 8

Answer. Since the difference of logarithms is the logarithm of the quotient, we rewrite this as

ln 2 

x  1

x  1

ln 2 8

which is, after exponentiating, the same as

x  1

x  1

which gives us x  1 8  x  1  , so that x 9  7.

  1. Find the derivative of the given function:

a) y ln ln x 

Answer. Use the chain rule: dy dx

ln x

d dx

ln x

x ln x

b) y log 2  x^2  1 

Answer. Remember that log 2 A ln A ln2, so y ln  x^2  1  ln 2. Then, use the chain rule:

dy dx

ln 2  x^2  1 

2 x

ln 2

x

x^2  1 

c) y

ex

2

x

Answer. Use the quotient rule carefully:

dy dx

x  2 xex

2

ex

2

x^2

2 e

x^2  x  2 ex^2

ex^2  2  x  2 

3. Solve:  ln x ln  x 

Answer. By the laws of exponents, this becomes  ln x  1  2 ln x. Squaring both sides, we get the equation

4 ln x ln x  2. Thus ln x 0, or ln x 4, giving the solutions x 1 e^4.

  1. Find the integrals:

a) 

ln x ^2  1

x

dx

Answer. Let u ln x , so du dx  x. Then

 ln x  2  1

x

dx   u^2  1  du

u^3 3

u  C

ln x ^3

ln x  C

b)  e sin^ x^ cos xdx

Answer. Let u sin x du cos xdx. Then

 e sin x^ cos xdx  eudu e sin^ x^^  C

c) 

xdx

3 x^2  1

Answer. Let u 3 x^2  1 du 6 xdx. Then

xdx

3 x^2  1

du u

ln 3 x^2  1   C

5. Solve the initial value problem  x  1  y  2 y y  1  1.

Answer. Separating variables, this becomes

dy y

2 dx

x  1 

Integrating both sides,

ln y 2 ln x  1  C

which exponentiates to y K  x  1  2 , where K eC. The initial values give 1 K  1  1  2 , so K 1  4, and

the solution is y  x  1  2 4.

6. If f  x  2  x ln x , find f  x .