Logarithms and Finance

Converting Log and Exponential Form

100

Convert to Exponential Form:

log_2(8)=x

2^x=8

200

Convert to Logarithmic Form:

4^y=x

log_4(x)=y

300

Convert to Exponential Form:

log_(x-1)(4)=2y

(x-1)^(2y)=4

400

Convert to Exponential Form:

2log_(3x)(5-z)=4y

(3x)^(2y)=5-z

or

(3x)^(4y)=(5-z)^2

500

Convert to Logarithmic Form:

e^(x+4)=2y-7

ln(2y-7)=x+4

Solving Log Equations with Log Properties

100

Solve for x:

log_3(x-3)=log_3(55)

x=58

200

Solve for x:

log_5(x+6)=log_5(3x)

x=3

300

Solve for x:

2ln(2)+ln(x)=ln(x+12)

x=4

400

Solve for x:

3log(4)-log(x)=log(2)

x=32

500

Solve for x:

2log(x)=log(3x+4)

x=4

-1 is an extraneous solution

Expanding/Condensing Logarithms

100

Condense the Logarithms:

log_3(2x)-log_3(5y)

log_3((2x)/(5y))

200

Completely Expand the Logarithm:

log((2x)/y)

log(2)+log(x)-log(y)

300

Condense the Logarithms:

2ln(3)-2ln(x)+4ln(y)

ln((9y^4)/x^2)

400

Condense the Logarithms:

3log(x)-4log(2)-5log(z)+3log(3)

log((27x^3)/(16z^5))

500

Completely Expand the Logarithm:

ln((3x^6y^7)/(7z^5))

ln(3)+6ln(x)+7ln(y)-ln(7)-5ln(z)

Solving Exponential Equations with Logs

100

Solve using Logarithms. Round the answer to the hundredth if necessary:

6^x=90

x=2.51

200

Solve Using Logarithms. Round the answer to the hundredth if necessary:

3^(7x)=108

x=0.61

300

Solve by Converting:

log_4(x)=5

x=1024

400

Solve using Logarithms. Round the answer to the hundredth if necessary:

e^(7x)=60

x=0.58

500

Solve using Logarithms. Round the answer to the hundredth if necessary:

4^(x-2)=100

x=5.32

Mathematics of Finance

100

June made an initial deposit of $5700 in an account for her son. Assuming an interest rate of 6% compounded
quarterly, how much will the account be worth in 15 years?

$13,926.35

200

If Bob deposits $5000 at the end of each year for 15 years in an account paying 6% interest compounded
annually, find the amount he will have on deposit.

 $116,379.85

300

In order to purchase a home, a family borrows $45,000 at an annual interest rate of 13%, to be paid back over a 30-year period in equal monthly payments. What is their monthly payment?

$497.79

400

Green Thumb Landscaping wants to build a $121,000 greenhouse in 2 years. The company sets up a sinking
fund with payments made quarterly. Find the payment into this fund if the money earns 8% compounded
quarterly.

$14,097.69

500

If $22,000 is invested in an account earning 4.5% interest compounded continuously, determine
how long it will take the money to quadruple. Round to the nearest year.

31 years