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a fost răspuns

a) ( 1 + 1/2 ) × ( 1 + 1/3 ) × ( 1 + 1/4 ) × ( 1 + 1/5)=
b) ( 1 - 1/2 ) × ( 1 - 1/3 ) × ( 1 - 1/4 ) ×
( 1 - 1/5 )=