Răspuns :
Este formula 1+2+2^2+...+2^n=2^(n+1) -1
Deci 2^(n+1) -1=2^10 -1
2^(n+1)=2^10
n+1=10
n=9
2^10 -1=1+2+2^2+2^3+...+2^9
Deci 2^(n+1) -1=2^10 -1
2^(n+1)=2^10
n+1=10
n=9
2^10 -1=1+2+2^2+2^3+...+2^9