Question

the nth term of an AP is given by Tn=10-6n. find the sum of first n terms of the AP.

Answer 1

Here we must apply a formulae i. e
S= n÷2(a+l) given:nth term = 10-6n
S= n÷2 (a+10-6n)
The ans may be = n÷2a+5n-3n^2
Correct or not plz check the answer

Answer 2

an=10-6n

Putting n=1

a1=10-6=4

a=4

a2=10-12=-2

a2=-2

d=-2-4=-6

Now S=n/2*[2a+(n-1)d]

=n/2*[8+(n-1)-6]

=n/2*[8-6n+6]

=n/2[14-6n]

=n/2*2[7-3n]

n*[7-3n]

=7n-3n²

Answer:=7n-3n²

Hope it helps