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2 years ago

Find the fifth roots of 243(cos 300° + i sin 300°).

1 answer:

7 0

In looking for the fifth roots, we will use De Moivre's theorem.
The formula for this problem is z^5 = 243 (cos 300 degress + i sin 300 degrees)

Where you'll also need the following data:
300/5 = 60
360/5 = 72
- you'll input these two after the cos and i sin (60+k*72) where k = 0,1,2,3,4

solution:

z^5 = 243 (cos 300 degrees + i sin 300 degrees)
z= 243^1/5 (cos 300 degrees + i sin 300 degrees)
z= 3 (cos (60 + k*72) degrees) + (i sin (60 + k*72) degrees)

so the following are the roots:

3 (cos 60 degrees + i sin 60 degrees)
3 (cos 132 degrees + i sin 132 degrees)
3 (cos 204 degrees + i sin 204 degrees)
3 (cos 276 degrees + i sin 276 degrees)
3 (cos 348 degrees + i sin 348 degrees)

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2 years ago

You deposit $300 in a savings account that pays 6% interest compounded semiannually. How much will you have at the middle of the

Makovka662 [10]

Answer:

The total amount accrued, principal plus interest, from compound interest on an original principal of $ 300.00 at a rate of 6% per year compounded 2 times per year over 0.5 years is $ 309.00.

The total amount accrued, principal plus interest, from compound interest on an original principal of $ 300.00 at a rate of 6% per year compounded 2 times per year over 1 year is $ 318.27.

Step-by-step explanation:

a) How much will you have at the middle of the first year?

Using the formula

$A\:=\:P\left(1+\frac{r}{n}\right)^{nt}$

where

Principle = P

Annual rate = r

Compound = n

Time = (t in years)

A = Total amount

Given:

Principle P = $300

Annual rate r = 6% = 0.06 per year

Compound n = Semi-Annually = 2

Time (t in years) = 0.5 years

To determine:

Total amount = A = ?

Using the formula

$A\:=\:P\left(1+\frac{r}{n}\right)^{nt}$

substituting the values

$A=300\left(1+\frac{0.06}{2}\right)^{\left(2\right)\left(0.5\right)}$

$A=300\cdot \frac{2.06}{2}$

$A=\frac{618}{2}$

$A=309$ $

Therefore, the total amount accrued, principal plus interest, from compound interest on an original principal of $ 300.00 at a rate of 6% per year compounded 2 times per year over 0.5 years is $ 309.00.

Part b) How much at the end of one year?

Using the formula

$A\:=\:P\left(1+\frac{r}{n}\right)^{nt}$

where

Principle = P

Annual rate = r

Compound = n

Time = (t in years)

A = Total amount

Given:

Principle P = $300

Annual rate r = 6% = 0.06 per year

Compound n = Semi-Annually = 2

Time (t in years) = 1 years

To determine:

Total amount = A = ?

so using the formula

$A\:=\:P\left(1+\frac{r}{n}\right)^{nt}$

so substituting the values

$A\:=\:300\left(1+\frac{0.06}{2}\right)^{\left(2\right)\left(1\right)}$

$A=300\cdot \frac{2.06^2}{2^2}$

$A=318.27$ $

Therefore, the total amount accrued, principal plus interest, from compound interest on an original principal of $ 300.00 at a rate of 6% per year compounded 2 times per year over 1 year is $ 318.27.

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2 years ago

Suppose you begin a job with an annual salary of $32,900. Each year you are assured of a 5.5% raise. What its the total amount t

olga2289 [7]

Answer: the total amount that you can earn in 15 years is $737245. Option C

Step-by-step explanation:

You receive an annual salary of $32,900 and each year, you are assured of a 5.5% raise. Assuming there was no raise, you get 100% of your previous salary each year. With a raise of 5.5%, you will get 100 + 5.5 = 105.5% of your previous salary for each year. This is a geometric progression and we want to determine the sum of 15 terms(15 years).

The formula for the sum of terms in a geometric progression is

Sn = [a(r^n - 1)]/ r - 1

Sn = sum of n terms

a = the first term

n = number of terms

r = common ratio

From the information given,

a = 32900

n = 15

r = 105.5/100 = 1.055

S15 = [32900(1.055^15 - 1)] / 1.055 - 1

S15 = [32900(2.23247649 - 1)] / 0.055

S15 = 32900 × 1.23247649) / 0.055

S15 = 737245.0277

S15 = $737245

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2 years ago