Question

8). Find 2+22+222+2222+ ... upto n terms.​

Answer 1

Answer:

2+22+222+2222+.......upto n terms

=  (2*1)(2*2)(2*3)(2*4)........(2*n)

brackett indicates one digit.

=2468......(2n)

Answer 2

Answer:

2/9[10/9*(10n-1)-n]

Step-by-step explanation:

2+22+222+2222................

2(1+11+111+1111...........). Remove common

Multiply and divide with 9.

=2/9(9+99+999+9999)

To get 9 subtract with 10.

=2/9(10-1+100-1,1000-1..................)

Taking positive one side and negative at one side

=2/9(10+100+1000+10000..........-1-1-1-1.......)

=2/9[10*(10n-1/10-1)-n]

=2/9[10*(10n-1/9)-n]

=2/9[10/9*(10n-1)-n]