Question

tìm X biết:1313/1212-X=1/1x2+1/2x3+1/3x4+1/4x5+1/5x6

Answer 1

\(\frac {1313}{1212} - x = \frac {1}{1 \times2} + \frac {1}{2 \times 3} \)\(+ \frac {1}{3 \times 4} + \frac {1}{4 \times 5} + \frac{1}{5 \times6}\)

\(\frac {13}{12} - x = 1 - \frac {1}{2} + \frac {1}{2} - \frac {1}{3} + \frac {1} {3} - \frac {1}{4} + \frac {1}{4} - \frac {1} {5} + \frac {1}{5} - \frac {1}{6}\)

\(\frac {13}{12} - x = 1 - \frac {1}{6}\)

\(\frac {13}{12} - x = \frac {5}{6}\)

\(x = \frac {13}{12} - \frac {5}{6}\)

\(x = \frac {1}{4}\)

So/Vậy \(x = \frac {1}{4}\)