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Explicație pas cu pas:
La al doilea:
A = a^1+2+...+1980
1+2+...+1980
=1980•1981:2
=1981 • 1980:2
= 1981 • 990
a^1981•990
B = (a^990)^1981
= a^ 990• 1981
A = a^1981•990
B = a^990•1981
A=B