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3 years ago

Which calculation should be used to calculate s9 for the arithmetic sequence an=3n-1

Mathematics

2 answers:

Ganezh [65]3 years ago

7 0

Answer: Choice A

S9 = (9/2)*(2+26)

===============================================

The formula is

Sn = (n/2)*(a1+an)

where

Sn = sum of the first n terms (nth partial sum)

n = number of terms

a1 = first term

an = nth term

In this case,

n = 9

a1 = 2 (plug in n = 1 into the formula an = 3n-1 and simplify)

an = a9 = 26 (plug n = 9 into the formula an = 3n-1 and simplify)

So,

Sn = (n/2)*(a1+an)

S9 = (9/2)*(2+26)

will help us find the sum of the first 9 terms of this arithmetic sequence

mario62 [17]3 years ago

3 0

Answer:

A. S9 = (9/2)*(2+26)

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pentagon [3]

Answer:

a) 3x-5=16

b) 30cm

Step-by-step explanation:

a) 5(x-1)=2(x+8)

5x-5=2x+16

5x-2x-5=16

3x-5=16

b) solving the equation gives x=7

put x=7 into first line, 5(7-1)=30cm

to check we can place it into second one as well

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5 0

3 years ago

Evaluate the expression below for m=350. 3.5m

aev [14]

Just plug in 350 for 'm':

$\sf 3.5m$

$\sf 3.5(350)$

Multiply:

$\boxed{\sf 1225}$

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3 years ago

What is the constant of proportionality of the relationship shown in the graph?

andrew11 [14]

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8 0

4 years ago

Read 2 more answers

145 is what percent of 620

Oksanka [162]

Hello There!

145 is 23.39% of 620

HOW TO SOLVE

Equation: Y = P% * X

We need to solve our equation for "P"

P% = Y/X

P% = 145/620

p = 0.2339

Convert decimal to percent:

Percent = 0.2339 * 100 = 23.39%

4 0

3 years ago

Suppose that you toss a fair six-sided {1,2,3,4,5,6} die and let X represent the outcome obtained. Find the expected volume of a

timofeeve [1]

Answer:

The expected volume of the box is 364 cubic inches.

Step-by-step explanation:

Since the die is fair, then P(X=k) = 1/6 for any k in {1,2,3,4,5,6}. Let Y represent the volume of the box in cubic inches. For how the box is formed, Y = X²*24. Thus, the value of Y depends directly on the value of X, and we have

(When X = 1) Y = 1²*24 = 24, with probability 1/6 (the same than P(X=1)

(When X = 2) Y = 2²*24 = 96, with probability 1/6 (the same than P(X=2)

(When X = 3) Y = 3²*24 = 216, with probability 1/6 (the same than P(X=3)

(When X = 4) Y = 4²*24 = 384, with probability 1/6 (the same than P(X=4)

(When X = 5) Y = 5²*24 = 600, with probability 1/6 (the same than P(X=5)

(When X = 6) Y = 6²*24 = 864, with probability 1/6 (the same than P(X=6)

As a consequence, the expected volume of the box in cubic inches is

E(Y) = 1/6 * 24 + 1/6*96 + 1/6*216+ 1/6*384+ 1/6*600+1/6*864 = 364

3 0

3 years ago