1) (9^25)^2:[(27^16):3]=3^(2x25x2):3^(3x16-1)=
=3^100:3^47=3^53
2)
a=1+3+3^2+3^3…….+3^99+3^100
3a= 3+3^2+3^3+3^4+……..3^100+3^101
3a-a=3+3^2+3^3+3^4+……..3^100+3^101-(1+3+3^2+3^3…….+3^99+3^100)
se reduc toti termenii, in afara de
ultimul termen din prima paranteza si primul termen din paranteza a doua
2a=3^101-1
a=(3^101-1):2