Question

Tim x, biet

1/2+1/6+1/12+1/20+1/30+1/x=1/42

PLEASE,HELP ME , minh tick cho

Answer 1

\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{x}=\frac{1}{42}\)

\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-......+\frac{1}{5}-\frac{1}{6}+\frac{1}{x}=\frac{1}{42}\)

\(1-\frac{1}{6}+\frac{1}{x}=\frac{1}{42}\)

\(\frac{5}{6}+\frac{1}{x}=\frac{1}{42}\)

\(\frac{1}{x}=\frac{1}{42}-\frac{5}{6}\)

\(\frac{1}{x}=\frac{-34}{42}\)

x=\(\frac{-21}{17}\)