Question

Please answer the third question.​

Answer 1

Step-by-step explanation:

We have, an = 5-6n ⇒ a1 = 5 - 6 x 1 = -1 So, the given sequence is an A.P with first term a = a1 = -1 and last term l = an = 5 - 6n Therefore the sum of n terms is given by: Sn= n/2 (a+l)= n/2 (-1+5-6n)=2n-3n