Question

If the common difference of an AP is 5, then what is a18 – a13? (A) 5 (B) 20 (C) 25 (D) 30

Answer 1

Answer:

given d=5

a18=a+(18-1) *d

a18=a+17*d

a13=a+12d

a18-a13=a+ 17*d - a - 12d

=5*d

=5*5

therefore a18-a13=25