Question

tính

Answer 1

Ta có: \(\frac{4}{77}+\frac{4}{165}+\frac{4}{285}\)

\(=\frac{4}{7\cdot11}+\frac{4}{11\cdot15}+\frac{4}{15\cdot19}\)

\(=\frac17-\frac{1}{11}+\frac{1}{11}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}=\frac17-\frac{1}{19}=\frac{12}{7\cdot19}\)

ta có: \(\frac{5}{84}+\frac{3}{120}+\frac{4}{285}\)

\(=\frac{5}{7\cdot12}+\frac{3}{12\cdot15}+\frac{4}{15\cdot19}\)

\(=\frac17-\frac{1}{12}+\frac{1}{12}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}=\frac17-\frac{1}{19}=\frac{12}{7\cdot19}\)

TA có: \(\left(\frac{4}{77}+\frac{4}{165}+\frac{4}{285}\right):\left(\frac{5}{84}+\frac{3}{120}+\frac{4}{285}\right)\)

\(=\frac{12}{7\cdot19}:\frac{12}{7\cdot19}\)

=1