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
bulgar [2K]
3 years ago
7

I need to know the next term in the sequence AND the nth term of all the sequences

Mathematics
1 answer:
ANEK [815]3 years ago
3 0

I see you already did the ones where you figured out the formula.  There's a fun way that doesn't require figuring out the formula, called a forward difference table.

Let's work out the first one to learn the technique.  We write the sequence and under it the forward differences,

2 5 10 17 26

3 5  7  9

2 2 2  

We got 3=5-2, 5=10-5, 7=17-10, etc and the same for subsequent lines.  Eventually we get to an all constant line and we stop.

To extend the table we just add some constants to the constant line and work our way back up:

2 5 10 17 26 37 50

3 5  7  9  11  13

2 2 2   2  2

So we get 11 as 9+2 and 37 as 26+11 for our answer which matches the answer you already got.

Let's do the ones you haven't.

2 8  18 32 50 72

6 10 14 18  22

4  4  4   4  

Answer: 72

3 9  19  33 51   73

6 10 14  18  22

4 4  4    4

Answer: 73

2 11 26 47 74  107

9 15 21 27  33

6 6  6    6

Answer: 107

Three's our limit so I'll leave the last one to you.

---

A comment says we need the functions.  They're all quadratics.  I'll tell you how they want you to do it and how to do it in general.

They just want you to recognize these are all pretty close to just u_n=n^2.   The one that goes 3 12 27 etc. we recognize as just u_n=3n^2.   The one that goes 2 8 18 is just u_n =2n^2.  The one that goes 3 9 19 is one more than that so u_n=2n^2+1. The one that goes 2 11 26... is one less than 3 12 27 so is u_n=3n^2-1.  Again I'll leave the last one.

----

We can do these quadratics in general.  Let's work from our difference table.  If we have

f(n) = an^2 + bn + c

and we form the difference table for f(1), f(2), f(3) we get

a+b+c   4a+2b+c   9a+3b+c

3a+b     5a+b

2a

so we can use the first columns of our difference tables to get our polynomial.  

2 8  18 32 50 72

6 10 14 18  22

4  4  4   4  

Answer: 72

So we have 2a=4, so a=2

3a+b=6, so b=6-3(2)=0

a+b+c=2 so c=2-0-2=0

That gives us the obvious answer

u_n = 2n^2

3 9  19  33 51   73

6 10 14  18  22

4 4  4    4

Answer: 73

We have 2a=4 again so a=2, 3a+b=2 so b=0, and a+b+c=3 so c=1 giving

u_n = 2n^2+1

2 11 26 47 74  107

9 15 21 27  33

6 6  6    6

Answer: 107

2a=6 gives a=3

3a+b=9 gives b=0

a+b+c=2 gives c= -1

u_n = 3n^2-1

You might be interested in
2(3²+4²)=? <br><br><br><br><br> WHATS THE ANSWER
yulyashka [42]

Answer:

50

Step-by-step explanation:

P- Parenthesis

E- Exponents

M- Multiplication

D- Division

A- Addition

S- Subtraction

(3²+4²)

3*3= 9     4*4= 16     16+9= 25      2(25)      25*2= 50

Hope this helped! (ノ◕ヮ◕)ノ*:・゚✧

( ゚д゚)つ Bye

7 0
3 years ago
If there are 2,400 students,<br> 52% are boys and 48% girls. <br> What is the ratio of boy and girl?
jek_recluse [69]

Answer:

13:12

Step-by-step explanation:

52% 2400 = 1248

48% 2400 = 1152

Reduce to 13/12 = 13:12

4 0
3 years ago
Read 2 more answers
Find the volume of a right circular cone that has a height of 2.1 m and a base with a diameter of 13.7 m. Round your answer to t
Basile [38]

Answer:V = 103.2 m³

Step-by-step explanation:

3 0
3 years ago
A car dealer offers a discount of 15% off the normal price of a car for cash.
motikmotik

Answer:

7200

Step-by-step explanation:

100/(100-15) * 6120 = 7200

6 0
3 years ago
I WILL REWARD BRAINLIEST
Step2247 [10]

Answer:

What is the total number of students who brought water bottles to lunch?

Step-by-step explanation:

4 0
3 years ago
Read 2 more answers
Other questions:
  • (2 x + 1):15=(x-1):7​
    14·2 answers
  • Angles L and M are supplementary. What is the sum of their measures? The sum of the measures of angles L and M is °.
    15·1 answer
  • Use a graphing calculator to sketch the graph of the quadratic equation, and then state the domain and range. y=-0.5x^2+0.7x-5.1
    15·2 answers
  • Oil is leaking from a tanker at the rate of R(t) = 2000e^(-0.2t) gallons per hour where t is measured in hours. How much oil lea
    9·1 answer
  • When a number is decreased by 10% of itself the result is 171. What is the number?
    15·1 answer
  • Interpret the 2 expressions below without evaluating them. 19-(6+6) and 19-6+6
    5·2 answers
  • When I need to reduce the number by 13%, just multiply it by the number ...​
    7·1 answer
  • Using a number cube and a
    6·1 answer
  • P l e a s e h e l p m me !!!
    5·2 answers
  • What is the probability of spinning a yellow?
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!