Question

Find 30 − 20 for the AP , + , + 2, + 3, … … ..​

Answer 1

Answer

Here the first term is a and the common difference is d.

Now, a

n

=a+(n−1)d

∴a

20

=a+19d ...(1)

a

30

=a+29d ...(2)

On subtracting (1) from (2), we get

a

30

−a

20

=10