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x([tex] \frac{1}{1 \times 3} + \frac{1}{3 \times 5} + \frac{1}{5 \times 7} + ... + \frac{1}{61 \times 63} ) = 2 - \frac{64}{63} [/tex]
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Răspuns :

Răspuns:

1/1-1/3=2/3

1/3-1/5=2/3×5

1/5-1/7=

X(1/1-1/3+1/3-1/5+1/5-1/7+...+1/61-1/63)1/2=2-64/63

X(1-1/63)1/2=2-64/63

X/2(62/63)=(63×2-64)/63

X32/63=(126-64)/63

X32/63=62/63

x=62/32=31/16