Question

C=5/2.1+4/1.11+3/11.2+1/2.15+13/15.4

 

Answer 1

\(C=\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)

\(\frac{1}{7}C=\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\)

\(\frac{1}{7}C=\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{28}\)

\(\frac{1}{7}C=\frac{1}{2}-\frac{1}{28}\)

\(\frac{1}{7}C=\frac{13}{28}\)

\(C=\frac{13}{28}:\frac{1}{7}\)

\(C=\frac{13}{4}\)

Vậy \(C=\frac{13}{4}\)