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2 years ago

6

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1 answer:

e-lub [12.9K]2 years ago

7 0

Answer:

HDUEHD ehvd to be a great day of school and I have a great day of school and

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Calculate the arithmetic sequence in which a9=17 and the common difference is d=-2.1

jek_recluse [69]

Answer:

$S_{31}=71.3$

Step-by-step explanation:

The nth term of an arithmetic sequence is given by the formula,

$U_n=a_1+(n-1)d$

We were given that the 9th term is $17$ .

$\Rightarrow 17=a_1+(9-1)(-2.1)$

$\Rightarrow 17=a_1+(8)\times(-2.1)$

$\Rightarrow 17=a_1-\frac{84}{5}$

$\Rightarrow 17+\frac{84}{5}=a_1$

$\Rightarrow a_1=\frac{169}{5}$

The sum of the first n-terms is given by the formula,

$S_n=\frac{n}{2}(2a_1+(n-1)d)$

To find $S_{31}$ , we substitute $n=31$ , $a_1=\frac{169}{5}$ and $d=-2.1$ .

$\Rightarrow S_{31}=\frac{31}{2}(2(\frac{169}{5}+(31-1)(-2.1))$

$\Rightarrow S_{31}=\frac{31}{2}(2(\frac{169}{5}+(30)(-2.1))$

$\Rightarrow S_{31}=\frac{31}{2}(\frac{23}{5})$

$\Rightarrow S_{31}=\frac{713}{10}$

$\Rightarrow S_{31}=71.3$

The correct answer is D

8 0

3 years ago

Read 2 more answers

Please help with number 7! :D please and thank you!

schepotkina [342]

Answer:

fraction

Step-by-step explanation:

any number between 0 and 1 is a fraction

3 0

3 years ago

Y=-155. Put in a table of 3 rows.

Alja [10]

Answer:

51.6666666667

Step-by-step explanation:

4 0

3 years ago

Spencer made a quilt for his cousin's doll. The quilt had a 7x7 array of different color square patches. If each patch is 1 3/4

Damm [24]

Answer:

$\frac{2401}{16}$ square inches

Step-by-step explanation:

Given:

The quilt made by Spencer had a 7×7 array of different color square patches such that each patch is $1\frac{3}{4}$ in long.

To find: the area of the whole quilt

Solution:

Side of each quilt = $7(\frac{3}{4})=7(\frac{7}{4})=\frac{49}{4}$

Quilt is in the form of a square such that area of square is given by $(side)^2$

Therefore, area of quilt = $(side)^2=(\frac{49}{4})^2 =\frac{2401}{16}$ square inches

3 0

3 years ago

What is the answer to 2937682+28373938

xxMikexx [17]

Answer: 31311620

Step-by-step explanation: Calculator

5 0

2 years ago