Find the sum of a finite geometric series.

2 answers:

4 0

Including the first year where they spend $2,000 dollars and it's added altogether: $9,282

Not including first year and it's added altogether: $10,210.2

If you're talking about the money they spent on only the 4th year:
1st year- $2,000
2nd year- $2,200
3rd year- $2,420
4th year- $2,662

If you don't count the year where they spend $2,000:
1st year: $2,200
2nd year: $2,420
3rd year: $2,662
4th year: $2,928.2

blsea [12.9K]2 years ago

3 0

Sum of a finite geometric series=a(r^(n) -1)/(r -1)
or
sum of a finite geometric series=a(1 - r^(n))/(1 - r)
the Smiths would spend a total of $2928.2 on clothing in 4 years

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Liam wants to save $6,265 to purchase a car. if $4,000 is deposited into an account at 7.5% interest, compounded monthly, how ma

timurjin [86]

To solve for time taken we use the compound formula:
A=P(1+r/100*n)^(n*t)
where:
A=future value
P=principle
r=rate
t=time
n=number of terms

6265=4000(1+7.5/(12*100))^(12t)
solving for t we get
1.56625=1.00625^12t
12t=72.0136
t=6.00 years
Answer: 6 years

5 0

2 years ago

A= [1, 3; 2, 1], B=[3, 6; -1, 1]. Find AB & BA if possible

steposvetlana [31]

Answer:

$AB\Rightarrow \quad \begin{bmatrix}0 & 9\\ 5 & 13\end{bmatrix}\\BA\Rightarrow \quad \begin{bmatrix}15 & 15\\ 1 & -2\end{bmatrix}$

Step-by-step explanation:

For two matrix P and Q, the product, say PQ is defined when:

The number of columns of P = The number of rows of Q

Since A is a 2×2 matrix and B is also a 2×2 matrix

Thus both AB and BA are possible.

So AB is:

$AB\Rightarrow\begin{bmatrix}1 & 3\\ 2 & 1\end{bmatrix}\begin{bmatrix}3 & 6\\ -1 & 1\end{bmatrix}\\AB\Rightarrow\quad \begin{bmatrix}3\times 1+3\times (-1) & 6\times 1+3\times 1\\3\times 2+1\times (-1) & 6\times 2+1\times 1\end{bmatrix}\\AB\Rightarrow \quad \begin{bmatrix}0 & 9\\ 5 & 13\end{bmatrix}$

BA is:

$BA\Rightarrow\begin{bmatrix}3 & 6\\ -1 & 1\end{bmatrix}\begin{bmatrix}1 & 3\\ 2 & 1\end{bmatrix}\\BA\Rightarrow\quad \begin{bmatrix}3\times 1+6\times 2 & 3\times 3+6\times 1\\(-1)\times 1+1\times 2 & (-1)\times 3+1\times 1\end{bmatrix}\\BA\Rightarrow \quad \begin{bmatrix}15 & 15\\ 1 & -2\end{bmatrix}$