I WILL GIVE BRAINLEST!!!!!!! 6/9x+57=8

How many terms are there in a geometric series if the first term is 4, the common ration is 3 and the sum of the series is 160

Marina CMI [18]

$\bf \qquad \qquad \textit{sum of a finite geometric sequence}
\\\\
S_n=\sum\limits_{i=1}^{n}\ a_1\cdot r^{i-1}\implies S_n=a_1\left( \cfrac{1-r^n}{1-r} \right)\quad 
\begin{cases}
n=n^{th}\ term\\
a_1=\textit{first term's value}\\
r=\textit{common ratio}\\
----------\\
a_1=4\\
r=3\\
S_n=160
\end{cases}$

$\bf 160=4\left( \cfrac{1-3^n}{1-3} \right)\implies 160=4\left( \cfrac{1-3^n}{-2} \right)\implies 160=-2(1-3^n)
\\\\\\
160=2(3^n-1)\implies \cfrac{160}{2}=3^n-1\implies 80=3^n-1
\\\\\\
81=3^n~~
\begin{cases}
81=3\cdot 3\cdot 3\cdot 3\\
\qquad 3^4
\end{cases}\implies 3^4=3^n\implies 4=n$

3 0

2 years ago

This is so confusing all of it makes no sense

Tom [10]

Answer:

D). $4\sqrt{2}$

Step-by-step explanation:

STEP 1a: Find the last angle of the triangle. ( which is angle A)

$A+90+45=180$

STEP 1b: Solve the equation for A by adding 90 and 45.

$A+135=180$

STEP 1c: Then Move all terms not containing A to the right side of the equation by subtracting 135 from both sides of the equation

$A=180-135$

STEP 1d: Subtract 135 from 180.

$A=45$

STEP 2a: Find side b next.

STEP 2b: The cosine of an angle is equal to the ratio of the adjacent side to the hypotenuse.

$cos(A)=\frac{adj}{hyp}$

STEP 2c: Substitute the name of each side into the definition of the cosine function.

$cos(A)=\frac{b}{c}$

STEP 2d: Set up the equation to solve for the adjacent side, in this case b.

$b=c*cos(A)$

STEP 2e: Substitute the values of each variable into the formula for cosine.

$b=8*cos(45)$

STEP 2f: Cancel the common factor of 2.

$a=4\sqrt{2}$

HOPE THIS HELPS!

4 0

2 years ago

Read 2 more answers

Plz hellppp -4(x-2) +5 = -10

vovangra [49]

Answer:

The answer is 5.75

Step-by-step explanation:

I used desmos

5 0

3 years ago

Read 2 more answers

The dimensions of a conical funnel are shown below: A conical funnel is shown with the height of the cone as 8 inches and the ra

ELEN [110]

Answer:

B

Step-by-step explanation:

r=3 in

h=8 in

Volume of funnel

$V=\frac{1}{3}\pi r^2h\\=\frac{1}{3} \times 3.14 \times 3^2 \times 8\\=75.36 in.^3\\time ~taken~to~drip out=\frac{75.36}{15}\\\approx 5.02~minutes.$

7 0

2 years ago

Read 2 more answers

-4(-6+9+4v+7v) what is the answer

r-ruslan [8.4K]

First step:
simplify the values in the parenthesis:
-4(3+11v)
Second step:
apply the distributive property:
-12-44v
The final answer (simplified) is -44v-12

4 0

3 years ago