Question

If the 8th term of an

a.P. Is 37 and the 15th term is 15 more than the 12th term, find the

a.P. Hence find the sum of the first 15 terms of the

a.P.

Answer 1

Step-by-step explanation:

8th term=37

a+7d=37- - -1

15th term=15+12th term

a+14d=15+a+11d

3d=15

d=5

putting value of d in 1,we get

a+7(5)=37

a=37-35

a=2

A.P. formed= a,a+d,a+2d- - -

=2,7,12- - -

sum of first 15 terms A.P=

n/2[2a+(n-1)d]

=15/2[2*2+(15-1)5]

=15/2[4+70]

=15/2*74

=37*15

=555