Question

find the sum of last ten terms of the a. p:8,10,12,.....,126

Answer 1

heya folk.!!!!

it's too easy

l"last term "=8
d"=10-8
d=2.

tn=l-(n-1)d

t10=126-(10-1)2

t10=126-18

t10=108

for this Ap 10th term is as a "first term =108 .

and last term is 126.

and
tn=,a+(n-1)d
126=a+(n-1)2

=)126+2=8+2n.

=)120=2n

=)n=60

sm=n/2*(108+126)

=)60/2(234)

=30*234

=)7020Ans .

hope it help you ☺

@rajukumar☺