Question

the sum of the first n terms of an arithmetic
Sequence
is 5n²+3n ,
a) Find Common differences
b)write down the sequence ?
c) what is the algebraic form for this sequence​

Answer 1

Step-by-step explanation:

n/2{2(5n square +3n)+(n-1)d}

Answer 2

Answer:

Step-by-step explanation:

Sₙ = 5n²+3n

a) common difference = 2xcoefficient of n²

                                  = 2x5

                                  = 10

              or

   first term,f = 5x1²+3x1 = 5+3 = 8

   sum of first two terms = 5x2²+3x2 = 5x4+6 = 20+6 =26

   second term = sum of first two - first term = 26-8 = 18

   common difference, d = a₂-f = 18-8 = 10

b) a₁ = 8

   a₂ = 18

   a₃ = 18+10 =28

   a₄ = 28+10 = 38

   sequence is 8, 18, 28, 38,..........

c) Xₙ = dn+(f-d)

       = 10n+(8-10)

       = 10n+-2

       = 10-2