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
lisabon 2012 [21]
3 years ago
7

1. The sum of first n terms of an arithmetic sequence is 3n²+4n

Mathematics
1 answer:
valentina_108 [34]3 years ago
5 0

Answer:

<h3>           a.  a₁=7,     b.  a_n=7n+1,    c.  a₂₀=141</h3>

Step-by-step explanation:

a.

 a_1=S_1=3\cdot1^2+4\cdot1=3+4=7

b.

   a_1+a_2=S_2\\\\a_1+a_1+d=3\cdot2^2+4\cdot2\\\\7+7+d=3\cdot4+8\\\\14+d=12+8\\\\d=6\\\\\\a_n=a_1+d(n-1)\\\\a_n=7+6(n-1)\\\\a_n=7+6n-6\\\\\underline{a_n=7n+1}

c.

 a_{20}=7\cdot20+1=141

You might be interested in
Johnny says multiplication always makes numbers bigger. Explain to Johnny why this isn’t true. Give more than one example to hel
yarga [219]

Answer:

Explained

Step-by-step explanation:

No, Multiplication does not always makes number bigger. When number is Multiplied by any number less than 1 the magnitude of the number decreases. Also any number multiplied by a negative number also reduces the number,

Example 5×2= 10 and 5×0.2= 1 clearly , 1<5

also, 5×(-2) = -10 which is also less than 5.

6 0
3 years ago
Zane spent $1.50 more than Taylor
Virty [35]
How much does Taylor has?
8 0
3 years ago
Help #2-8 please thank you !
lapo4ka [179]
2. $1.75
3. $1.65
4. $1.05
5. $1.55
6. $1.20
7. $1.50
8. $1.29
3 0
3 years ago
Shannon is putting a fence around the garden ,except where there is a gate that is 3 feet wide .one foot of the fence cost $43.
AfilCa [17]
43 x 3 = 129 divided by 2 = 64.5
7 0
3 years ago
Read 2 more answers
What’s the opposite of negative two
allsm [11]

Answer: The answer is two

Step-by-step explanation: If you look for opposites of a number its either negative or positive. So when the answer is negative, the opposite is positive and if the answer is positive, the opposite is negative.

8 0
3 years ago
Read 2 more answers
Other questions:
  • on monday it rained 2 1/3 inches of rain. today the total rain for monday and tuesday was 3 7/8 inches. how many inches did it r
    15·1 answer
  • Which property is illustrated by the statement (4+6.1)+7=4+(6.1+7)
    6·2 answers
  • What is 3 divided 76
    8·2 answers
  • Find the vertex: y= -4x^2-8x-7
    8·1 answer
  • Round 481 to the nearest<br> tens place?
    8·1 answer
  • What is the next term of the geometric sequence?<br> 3, 12, 48,
    6·2 answers
  • Can someone help me out?
    11·1 answer
  • I'll give brainliest ​
    15·1 answer
  • When a number is multiplied by 5 before subtracting from 78 the result obtained is the same as three times the sum of the number
    7·1 answer
  • 104, 116, 128, 140 in the 5th term sequence<br>​
    8·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!