Question

the sum of first n terms of an arithmetic progression is 210 and sum of its first N -1 terms is 171 the first term is 3 then write the arithmetic progression ​

Answer 1

Answer:

3+7+11+....+39

Step-by-step explanation:

sum of first n terms = 210

n-1 terms sum= 171

so nth term=210-171=39

sum of n terms=n/2(first + last term)

210=n/2(3+39)

so n=10

nth term=first term +(n-1)common difference

39=3+(10-1)d

so d=4

Hence series is 3(+4)7(+4)....39