Question

the sum of first 15 terms of AP is 750 and its first term is 15 find its 20th term​

Answer 1

Step-by-step explanation:

S15= 15/2{2a+(15-1)d}

and, a=15

so,

750=15/2{2x15+14d}

1500/15=30+14d

100-30=14d

70/14=d

d=5

Therefore,

A20=a+19d

=15+19(5)

=15+95

=110

110 is the answer