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(1pe 1×2 + 1 pe 2×3 +...+ 1 pe 19 ×20 ) : [(19 pe 4 ) la puterea 5 : (19pe4) la puterea 2 : (19pe4)la puterea 2 ] = ????

Răspuns :

(1/1•2+1/2•3+...+1/19•20):[(19/4)^5:(19/4)²:(19/4)²
(1/1-1/2+1/2-1/3+1/3+...+1/19-1/20):(19/4)¹
(1/1-1/20):19/4
(20/20-1/20)•4/19
19/20•4/19
1/5

Sper ca te-am ajutat!