Question

1 supra 1+2+3+4+.....+10=?
Desfășurat, va rog

Answer 1

$\frac{1}{1 + 2 + 3 + 4 + ... + 10} = \\ \\ \frac{1}{ \frac{n(n + 1)}{2} } = \\ \\ \frac{1}{ \frac{10(10 + 1)}{2} } = \\ \\ \frac{1}{ \frac{10 \times 11}{2} } = \\ \\ \frac{1}{ \frac{110}{2} } = \\ \\ \frac{1}{55}$

Answer 2

$\frac{1}{1+2+3+4+...+10}$

=$\frac{1}{10*(10+1)/2}$

=$\frac{1}{10*11/2}$

=$\frac{1}{5*11}$

$\frac{1}{55}$