Question

find the sum of all odd integers btw 150&275​

Answer 1

a= 151 d=2 , an = 273

Sn= n/2{2a+(n-1)d}

= n/2 {302+(n-1) 2}

= n/2 {300 +2n }

= n/2 (300+2n)

Sn = 300n+2n² / 2

An= a+(n-1)d

273 = 151 +2n-2

273 = 149 +2n

124= 2n

n= 62

put n in An

Sn= 300×62 + 2×62² / 2

= 26288