Question

If the common difference of an ap is 3 find the value of a20-a15

Answer 1

Answer:

Common difference, d=3

General term of an AP,

a=a1+(n-1)d

a1= 1st term

and n= nth term

therefore, a20 = a1 + (20-1)d

a20 = a1 + 19d

Similarly, a15 = a1 + 14d

Now, a20 - a15 = (a1 + 19d) - (a1 + 14d)

= a1 + 19d - a1 - 14d

= 19d - 14d

= 5d

= 5 × 3 (d = 3)

= 15

Answer 2

hope this will helpful!!