Question

9 x 10 + 9 x 10^2 + 9 x 10^3 + ... + 9 x 10^108 + 10
urgent

Answer 1

9 x 10 + 9 x 10^2 + 9 x 10^3 + ... + 9 x 10^108 + 10=

=9(10+10^2+10^3+....+10^108) +10

=9(10^109-10)/9+10

=10^109-0+10

=10^109

Am utilizat formula:

a+a^2+a^3+.....+a^n=[a^(n+1) –a]/(a-1)