Question

Find the sum of n terms of an A.P. whose nth terms is given by an =5-6n.

Answer 1

Answer:

Given: tn = 5 - 6n

Put n=1, t1= -1

n=2, t2= -7

n=3,t3= -13

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

= n/2[2(-1)+(n-1)-6]

= n/2[-2-6n+6]

=n/2(4-6n)

=> n(2-3n)