All categories

3 years ago

Determine the number of terms n : a 1 = 15, a n = 79, S n = 423

Mathematics

1 answer:

yuradex [85]3 years ago

3 0

Answer:

The number of terms in the sequence is 9

Step-by-step explanation:

We want to get the number of terms

Mathematically, we have the formula for the sum of terms in an arithmetic sequence as

$sn = \frac{n}{2} (a + 1)$

a represents the first terms, and i represent the last term

$423 = \frac{n}{2} (15 + 79) \\ \\ 423 \times 2 = 94(n) \\ \\ 94n = 846 \\ \\ n = \frac{846}{94} \\ \\ n = 9$

You might be interested in

Write an algebraic expression for<br><br> "10 less than h"<br><br> Answer (no spaces in answer)

Agata [3.3K]

Answer:

h-10

Step-by-step explanation:

just subtract 10 from h

7 0

3 years ago

Read 2 more answers

Given $a \equiv 1 \pmod{7}$, $b \equiv 2 \pmod{7}$, and $c \equiv 6 \pmod{7}$, what is the remainder when $a^{81} b^{91} c^{27}$

Blizzard [7]

$\begin{cases}a\equiv1\pmod7\\b\equiv2\pmod7\\c\equiv6\pmod7\end{cases}$

$a^{81}\equiv1^{81}\equiv1\pmod7$

$b^{91}\equiv2^{91}\pmod7$

$2^{91}\equiv(2^3)^{30}\times2^1\equiv8^{30}\times2\pmod7$
$8\equiv1\pmod7$
$2\equiv2\pmod7$
$\implies2^{91}\equiv1^{30}\times2\equiv2\pmod7$

$c^{27}\equiv6^{27}\pmod7$

$6^{27}\equiv(-1)^{27}\equiv-1\equiv6\pmod7$

$\implies a^{81}b^{91}c^{27}\equiv1\times2\times6\equiv12\equiv5\pmod7$

6 0

3 years ago

5/k = 15/20 what would the k be?

mash [69]

Answer:

20/3

Step-by-step explanation:

5/k=15/20

5/k=3/4

5 x 4/3 = k

k=20/3

3 0

4 years ago

Write an inequality that compares-6, 3, and 5

olga_2 [115]

Is that 6 or negative 6? I'll do both situations, as I can't tell (sorry!)

With negative 6:

-6 < 3 < 5

With positive 6:

3 < 5 < 6

8 0

3 years ago

Which number is a factor of 14 but not a multiple of 7??

Ilya [14]

Answer:

Step-by-step explanation:

Write out all the factors for 14

Then write out the multiples of 7

Compare the numbers then find the greatest number in 14's factors that isn't in 7's multiples

4 0

3 years ago