Question

the first and last terms of an ap are 17 and 350 respectively if Yeh common difference is 9 then find how many terms are there are what is their sum

Answer 1

a=17
an=350
an=a+(n-1)d
or, 350=17+(n-1)9
or, 350=17+9n-9
9n=350-8
n=342/9
n=38ans....

Answer 2

Here is your solution

Given:-

a= first term =17

d= common difference =9

n = number of terms

tn=a+(n-1)d

350 = 17 + (n-1) 9

9n = 342

n. = 38

Sum of AP =( n/2)[2a+(n-1)d]

= (38/2)[ 2×17+ 37*9]

= 19 [34 +333]

= 6973

Hope it helps you