1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Mama L [17]
3 years ago
6

Find Sn for the arithmetic series 5+7+9 + … and determine the value of n for which the series has sum 165.

Mathematics
1 answer:
SVETLANKA909090 [29]3 years ago
4 0

Answer:

see explanation

Step-by-step explanation:

the sum to n terms of an arithmetic sequence is

S_{n} = \frac{n}{2}[2a + (n - 1)d ]

where d is the common difference and a is the first term

here d = 9 - 7 = 7 - 5 = 2 and a = 5, hence

S_{n} = \frac{n}{2}[(2 × 5) + 2(n - 1) ]

                        = \frac{n}{2}(10 + 2n - 2)

                        = \frac{n}{2}(2n + 8)

                        = n² + 4n

When sum = 165, then

n² + 4n = 165 ← rearrange into standard form

n² + 4n - 165 = 0 ← in standard form

(n + 15)(n - 11) = 0 ← in factored form

equate each factor to zero and solve for n

n + 15 = 0 ⇒ n = - 15

n - 11 = 0 ⇒ n = 11

but n > 0 ⇒ n = 11



You might be interested in
Please answer!!!!!!
Crazy boy [7]

Answer:

(this isnt a mathematics question, it's science, btw)

Indeed, you are correct. It is 1. I think.

Because you get one allele from each parent, to make up 2 alleles per offspring.

Hope that helps!

4 0
3 years ago
I need the answer fast please
shusha [124]
The diameter of the circle is needed. But to solve, you would simply multiply the diameter of the circle by pi (3.14).
3 0
3 years ago
What is the solution to (x+6)(x+2)=60
Citrus2011 [14]
Distribute to eliminate the parenthesis

x^2 + 2x + 6x + 12 = 60

Combine like terms

x^2 + 8x + 12 = 60

Subtract 60 from both sides

x^2 + 8x - 48 = 0

Factor the equation

(x+12)(x-4)=0
x+12=0
x+4=0

x= -12 and -4
5 0
3 years ago
Will bought 36 balloons and divided them evenly into 6 groups. How many balloons are in each group? ​
fredd [130]

Answer:

6

Step-by-step explanation:

Since the 36 balloons are being divided evenly into 6 groups, you divide the 36 by 6. Once you do this, you are left with 6.

3 0
3 years ago
Read 2 more answers
Round 80531 to the nearest thousand.
Iteru [2.4K]
That would be 8,1000
6 0
3 years ago
Read 2 more answers
Other questions:
  • How do you Graph 4x=10
    5·1 answer
  • Brian bought x apples and some oranges. Brian bought 3 more oranges than apples.
    7·1 answer
  • A 12-ounce Pepsi contains 54 mg of caffeine. A can of Red Bull (8.2 oz) has 80 mg of caffeine.
    9·2 answers
  • Write a polynomial function in standard form with zeros at −3, −1, and 1.
    15·1 answer
  • Which statement explains Joni’s error?
    14·1 answer
  • ****BRAINLIEST GOES TO THE FIRST CORRECT ANSWER****
    7·1 answer
  • I NEED HELP ASAP WILL MARK BRAINLIST. NOTE: EVERYTHING IS ALREADY ANSWERD ALL I NEED HELP WITH IS QUESTION 8 AND 9 PLEASE
    12·2 answers
  • A computer tracking chip company wants to test their chips. They marked 32 birds by attaching computer chips to their legs. Late
    7·1 answer
  • Plsss Help!! Will mark brainiest!! Due soon!!
    9·2 answers
  • A store is having a sale with 10% off everything.
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!