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ANEK [815]
3 years ago
8

What is the sum of the geometric series in which a1 = −5, r = 3, and an = −405?

Mathematics
1 answer:
marysya [2.9K]3 years ago
3 0
An = a1 * r^(n-1)

-405 = -5*3^(n-1)

3^(n-1) = 81

3^4 = 81  so n-1 = 3  and n =  4

Sn  = S4  =  -5 (1 - 3^4)   / ( 1 - 3)   =  400 / -2 = -200 Answer
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nydimaria [60]

Answer:

12/5 or 2 2/5

Step-by-step explanation:

3/5+3/5+3/5+3/5

=> (3+3+3+3) / 5

=> 12/5

=> 2 2/5

Hope it helps......

8 0
3 years ago
Read 2 more answers
A cylinder has a diameter of 6 feet. the volume of the cylinder is 36/5π cubic feet.
Anton [14]

Answer:

Height of cylinder is \frac{4}{5}\ ft.

Step-by-step explanation:

Diameter of cylinder, D = 6 feet

Relation between Radius, R and diameter, D is given by:

R = \dfrac{D}{2}

So, radius, R = \frac{6}{2} \Rightarrow 3 feet

Let height of cylinder be h feet.

Formula for volume of cylinder is given by:

V = \pi R^{2} H

Where, R is the radius of base of cylinder

and H is the height of cylinder

We are given that,

V = \dfrac{36 \pi}{5} ft^{3}

Using formula for volume, V = \pi R^{2} H

\dfrac{36\pi}{5} = \pi \times 3^{2} \times h\\\Rightarrow \dfrac{36\pi}{5} = \pi \times 9 \times h\\\Rightarrow h = \dfrac{4}{5} ft

Hence, Height of cylinder is \frac{4}{5}\ ft.

7 0
3 years ago
Given the value of the hypotenuse c for a 30°-60°-90° triangle, write the
zlopas [31]

Answer:

a= c/2

b= (c/2)×√3

side b is the side with the 60 degree angle.

side a is the side with the 30 degree angle.

using the theorem that the side with the 60 degree × 2 = length of side c and the side with the 60 degree × √3 = b.

I get the following equations shown above.

6 0
3 years ago
F(x+h) = (x+h)² + 3(x+h)^3<br><br> How would I distribute this?
Leno4ka [110]

Answer:

f(x + h) = 3x³ + x² + 9h²x + 3h³ + h² + 9hx² + 2hx

General Formulas and Concepts:

  • Order of Operations: BPEMDAS
  • Distributive Property
  • Expand by FOIL (First Outside Inside Last)
  • Combining like terms

Step-by-step explanation:

<u>Step 1: Define function</u>

f(x) = x² + 3x³

f(x + h) is x = x + h

<u>Step 2: Simplify</u>

  1. Substitute:                              f(x + h) = (x + h)² + 3(x + h)³
  2. Expand by FOILing:               f(x + h) = (x² + 2hx + h²) + 3(x + h)³
  3. Rewrite:                                  f(x + h) = (x² + 2hx + h²) + 3(x + h)²(x + h)
  4. Expand by FOILing:               f(x + h) = (x²+2hx+h²) + 3(x² + 2hx + h²)(x+h)
  5. Distribute/Expand:                 f(x + h) = (x²+2hx+h²) + 3(x³+3hx²+3h²x+h³)
  6. Distribute 3:                            f(x + h) = (x²+2hx+h²)+(3x³+9hx²+9h²x+3h³)
  7. Combine like terms:               f(x + h) = 3x³+x²+9h²x+3h³+h²+9hx²+2hx
3 0
3 years ago
Help plz:))) I’ll mark u brainliest
dybincka [34]

Answer:

a

Step-by-step explanation:

8 0
3 years ago
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