Answer:

Your input 0.8,1.2,1.6,2 appears to be an arithmetic sequence

Find the difference between the members

a2-a1=1.2-0.8=0.4

a3-a2=1.6-1.2=0.4

a4-a3=2-1.6=0.4

The difference between every two adjacent members of the series is constant and equal to 0.4

General Form: an=a1+(n-1)d

an=0.8+(n-1)0.4

a1=0.8   (this is the 1ST member)

an=2  (this is the last/nth member)

d=0.4  (this is the difference between consecutive members)

n=4  (this is the number of members)

Sum of finite series members

The sum of the members of a finite arithmetic progression is called an arithmetic series.

Using our EXAMPLE, consider the sum:

0.8+1.2+1.6+2

This sum can be found QUICKLY by taking the number n of terms being added (here 4), multiplying by the sum of the first and last number in the progression (here 0.8 + 2 = 2.8), and dividing by 2:

n(a1+an)2

4(0.8+2)

     2

The sum of the 4 members of this series is 5.6

This series corresponds to the following straight line y=0.4x+0.8

Finding the nthelement

a1 =a1+(n-1)*d =0.8+(1-1)*0.4 =0.8

a2 =a1+(n-1)*d =0.8+(2-1)*0.4 =1.2

a3 =a1+(n-1)*d =0.8+(3-1)*0.4 =1.6

a4 =a1+(n-1)*d =0.8+(4-1)*0.4 =2

a5 =a1+(n-1)*d =0.8+(5-1)*0.4 =2.4

a6 =a1+(n-1)*d =0.8+(6-1)*0.4 =2.8

a7 =a1+(n-1)*d =0.8+(7-1)*0.4 =3.2

a8 =a1+(n-1)*d =0.8+(8-1)*0.4 =3.6

a9 =a1+(n-1)*d =0.8+(9-1)*0.4 =4

a10 =a1+(n-1)*d =0.8+(10-1)*0.4 =4.4

a11 =a1+(n-1)*d =0.8+(11-1)*0.4 =4.8

a12 =a1+(n-1)*d =0.8+(12-1)*0.4 =5.2

a13 =a1+(n-1)*d =0.8+(13-1)*0.4 =5.6

a14 =a1+(n-1)*d =0.8+(14-1)*0.4 =6

a15 =a1+(n-1)*d =0.8+(15-1)*0.4 =6.4

a16 =a1+(n-1)*d =0.8+(16-1)*0.4 =6.8

a17 =a1+(n-1)*d =0.8+(17-1)*0.4 =7.2

a18 =a1+(n-1)*d =0.8+(18-1)*0.4 =7.6

a19 =a1+(n-1)*d =0.8+(19-1)*0.4 =8

a20 =a1+(n-1)*d =0.8+(20-1)*0.4 =8.4

a21 =a1+(n-1)*d =0.8+(21-1)*0.4 =8.8

a22 =a1+(n-1)*d =0.8+(22-1)*0.4 =9.2

a23 =a1+(n-1)*d =0.8+(23-1)*0.4 =9.6

a24 =a1+(n-1)*d =0.8+(24-1)*0.4 =10

a25 =a1+(n-1)*d =0.8+(25-1)*0.4 =10.4

a26 =a1+(n-1)*d =0.8+(26-1)*0.4 =10.8

a27 =a1+(n-1)*d =0.8+(27-1)*0.4 =11.2

a28 =a1+(n-1)*d =0.8+(28-1)*0.4 =11.6

a29 =a1+(n-1)*d =0.8+(29-1)*0.4 =12

Sorry It's in English don't know to answer in marathi