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Paul [167]
3 years ago
7

Find the sum of a finite geometric sequence from n = 1 to n = 8, using the expression −2(3)^n − 1.

Mathematics
1 answer:
Kazeer [188]3 years ago
6 0
The sum if the geometric sequence given by:
an=-2(3)^(n-1)
will be:
when:
n=1
an=-2
when n=2
a2=-6
when n=3
a3=-18

when n=4
a4=-54

when n=5
a5=-162

when n=6
a6=-486

when n=7
a7=-1458

when n=8
a8=-4374

thus the summation of the term will be:
Sn=(-4374+-1458+-486+-162+-54+-18+-6+-2)
Sn=-6560
the answer is -6560

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Step-by-step explanation:

In the expression a^n, for integer values of n greater than 1, there are n factors. For example, a^2 = a * 2 (2 factors), a^3 = a * a * a (3 factors), etc.

For a non-negative value of a, a^n is non-negative for all values of n.

If a is negative, and n is even, then a^n is non-negative.

If a is negative, and n is odd, then a^n is negative.

|a| is non-negative for all values of a.

sqrt_n(a^n) is negative for negative a and odd n, but |a| is always non-negative, so sqrtn(a^n) cannot equal |a| for odd n.

8 0
3 years ago
The sum of the digits of a two-digit number is 9. When the digits are reversed, the new number is 9 more than the original numbe
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9514 1404 393

Answer:

  d.  45

Step-by-step explanation:

You can check the offered answers. You will find that the difference from reversing the digits will only be 9 if the digits differ by 9/9 = 1.

The original number is 45.

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<em>Check</em>

  45 + 9 = 54 . . . with the digits reversed

4 0
3 years ago
Please find the slope of (-2, 4) and (3, -5)
DIA [1.3K]

Answer:

The slope of the line = m = -9/5

Step-by-step explanation:

Given the points

  • (-2, 4)
  • (3, -5)  

Determining the slope between (-2, 4) and (3, -5)

(x₁, y₁) = (-2, 4)

(x₂, y₂) = (3, -5)

Using the formula

Slope = m =  [y₂ - y₁] /  [x₂ - x₁]  

                 =  [-5 - 4] / [3 - (-2)]

                 = [-9] / [3 + 2]

                 = -9/5

Thus, the slope of the line = m = -9/5  

8 0
3 years ago
Which expression shows the perimeter of the triangle in simplest form?
ankoles [38]

Answer:

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Step-by-step explanation:

A perimeter is just the sum of all sides of a shape.

First, write an equation to add all sides of the triangle:

(x + 4) + (3x - 2) + (2x + 1)

What is inside the parentheses is all already simplified. Also, it is addition, so the order in which we add does not matter. So, we can now get rid of the parentheses and combine like terms:

x + 3x + 2x + 4 -2 + 1

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And that's our final answer: 6x + 3

I would appreciate brainliest, have an amazing day!

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