Question

, a = 10, d = 7 - 10 = -3 l= -62
1= a + (n - 1)d​

Answer 1

Step-by-step explanation:

Here we are given last term(l)= 350 , a= 17 and d= 9 l= a+(n-1)d 350= 17+(n-1)9 350-17= (n-1)9 333/9= n-1 37+1= n 38=n so we have total number of terms 38 and we know sum= n/2(a+l) after putting all values in formula sum= 38/2(17+350) sum= 19*367 sum=6973

Let first term of AP = a

Last term of AP = l

common difference = d

l =a + (n-1)*d

=>350 = 17 + (n-1)*9 (Given l =350, a = 17 and d = 9)

=>350-17 = (n-1)*9

=>333 = (n-1)*9

=>n-1 = 333/9

=> n-1 = 37

=>n = 37+1

=> n =38

Now sum of AP = (n/2)*(a + l)

=> (38/2)*(17 + 350)

=> 19*367

=> 6973

So number of terms in AP is 38 and sum is 6937

Answer 2

n=4 is the correct answer and mark me as brainlist and folow me