Question

❣️ hello everyone ❣️ please answer my question ✨✨. I will be thankful to you​

Answer 1

From the formula of sum of first n terms which they gave we can find the all terms.

a1 = 5[1]^2/2+3[1]/2

a1 =5/2+3/2

a1 =8/2

a1=4

in the same way

a1 + a2  nothing but sum of 2 terms

a1+a2= 5[2].[2]/2 + 3[2]/2

4+a2=10+3

4+a2=13

a2=9

therefore   series are 4 , 9 , 14 , 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . n

a20 = a + 19 d

as d= 9-4=5

a20 = 4 + 19.5

a20 =99

and nth term is an = a+ [n-1]d

an=4+[n-1]5

an = 4+5n-5

an = 5n-1 //

Answer 2

Answer's in the pic............^_________^