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Arithmetic Progression - $@mEe
Arithmetic Progression - $@mEe
In mathematics, an arithmetic progression (AP) or arithmetic 
sequence is a sequence of numbers such that the difference 
between the consecutive terms is constant. For instance, the 
sequence 5, 7, 9, 11, 13, 15 … is an arithmetic progression with 
common difference of 2.
A finite portion of an arithmetic progression is called a finite 
arithmetic progression and sometimes just called an arithmetic 
progression. The sum of a finite arithmetic progression is called 
an arithmetic series.
3 , 7 , 11 , 15 , 19 , 23 …… 
: Commom Difference (d) = 4 (11 , 15) 
: Starting Number (a) = 3
If the initial term of an arithmetic progression is and the 
common difference of successive members isd, then 
thenth term of the sequence:
3 , 7 , 11 , 15 , 19 , 23 …… 
Each time you want another term in the sequence you’d add d. 
This would mean the second term was the first term plus d. The 
third term is the first term plus d plus d (added twice). The 
fourth term is the first term plus d plus d plus d (added three 
times). So you can see to get the nth term we’d take the first term 
and add d (n - 1) times. 
a a n d n   1 
Try this to get the 5th term. 
3 5 14 3 16 19 5 a      
1 2 3
a 
1 2 3 4
Arithmetic Progression - $@mEe
a = 1 
d = 3
The fourth term is 3 and the 20th term is 35. Find the first term and both a 
term generating formula and a recursive formula for this sequence. 
How many differences would you add 
to get from the 4th term to the 20th 
term? 
3 35 4 20 a  a  
a a 16d 20 4   Solve this for d d = 2 
The fourth term is the first term plus 3 
common differences. 
a a 3d 4 1 3   (2) 
35 3 
3 1 a   We have all the info we need to express these sequences.
The sum ofn terms, we find as, 
Sum = n [(first term + last term) / 2] 
=Now last term will be = a + (n-1) d 
Therefore, 
Sum(Sn) =n [{a + a + (n-1) d } /2 ] 
= n/2 [ 2a + (n+1)d]
•Solution. 
1) First term is a = 100 , an = 500 
2) Common difference is d = 105 -100 = 5 
3) nth term is an = a + (n-1)d 
4) 500 = 100 + (n-1)5 
5) 500 - 100 = 5(n – 1) 
6) 400 = 5(n – 1) 
7) 5(n – 1) = 400 
8) 5(n – 1) = 400 
9) n – 1 = 400/5 
10) n - 1 = 80 
11) n = 80 + 1 
12) n = 81 
Hence the no. of terms are 81.
Arithmetic Progression - $@mEe

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Arithmetic Progression - $@mEe

  • 3. In mathematics, an arithmetic progression (AP) or arithmetic sequence is a sequence of numbers such that the difference between the consecutive terms is constant. For instance, the sequence 5, 7, 9, 11, 13, 15 … is an arithmetic progression with common difference of 2.
  • 4. A finite portion of an arithmetic progression is called a finite arithmetic progression and sometimes just called an arithmetic progression. The sum of a finite arithmetic progression is called an arithmetic series.
  • 5. 3 , 7 , 11 , 15 , 19 , 23 …… : Commom Difference (d) = 4 (11 , 15) : Starting Number (a) = 3
  • 6. If the initial term of an arithmetic progression is and the common difference of successive members isd, then thenth term of the sequence:
  • 7. 3 , 7 , 11 , 15 , 19 , 23 …… Each time you want another term in the sequence you’d add d. This would mean the second term was the first term plus d. The third term is the first term plus d plus d (added twice). The fourth term is the first term plus d plus d plus d (added three times). So you can see to get the nth term we’d take the first term and add d (n - 1) times. a a n d n   1 Try this to get the 5th term. 3 5 14 3 16 19 5 a      
  • 9. a 1 2 3 4
  • 11. a = 1 d = 3
  • 12. The fourth term is 3 and the 20th term is 35. Find the first term and both a term generating formula and a recursive formula for this sequence. How many differences would you add to get from the 4th term to the 20th term? 3 35 4 20 a  a  a a 16d 20 4   Solve this for d d = 2 The fourth term is the first term plus 3 common differences. a a 3d 4 1 3   (2) 35 3 3 1 a   We have all the info we need to express these sequences.
  • 13. The sum ofn terms, we find as, Sum = n [(first term + last term) / 2] =Now last term will be = a + (n-1) d Therefore, Sum(Sn) =n [{a + a + (n-1) d } /2 ] = n/2 [ 2a + (n+1)d]
  • 14. •Solution. 1) First term is a = 100 , an = 500 2) Common difference is d = 105 -100 = 5 3) nth term is an = a + (n-1)d 4) 500 = 100 + (n-1)5 5) 500 - 100 = 5(n – 1) 6) 400 = 5(n – 1) 7) 5(n – 1) = 400 8) 5(n – 1) = 400 9) n – 1 = 400/5 10) n - 1 = 80 11) n = 80 + 1 12) n = 81 Hence the no. of terms are 81.