find rth term of AP then the sum of 1st nth term is 2n+3n^2?

Question

class 11th isce board maths question

Answer 1

me assume yu talk bout arithmetik sequens...

hav a start number & add same number eech time tu get next number

sum av such progreshun=n*(term 1+last term)/2

look at first 2 terms...sum=term1+term2=n*(term1+term2)/2

=2n+3*n*n=4+12=16  (n=2)

how bout n=1?, 2n+3n*n=5.....first term=5

plug intu yer formula with n=2, yu get sum av 2 terms=16

sins term 1=5, term 2=11...step size=6

Answer 2

look at first 2 terms...sum=term1+term2=n*(term1+term2)/2

=2n+3*n*n=4+12=16  (n=2)

how bout n=1?, 2n+3n*n=5.....first term