Question

+9+13 +17 T... TUI).
UULLOOOO
6 Which term of the AP 15, 11, 7, ... is (-13)? Also find the sum
(15+11+ 7 + ... + (-13)}.
7. Find the sum of all two-digit whole numbers divisible by 3.
8. Find the sum of all even numbers between 5 and 100.
9. Find the sum of all natural numbers less than 100 which are divisible
by 6.
[CBSE 2006)​

Answer 1

Step-by-step explanation:

a=15

d=11-15=-4

Let an =-13

a+(n-1)d=-13

15+(n-1)-4=-13

-4(n-1)=-13-15

-4(n-1)=-28

n-1=-28÷-4

n-1=7

n=7+1=8

n=8