C = \(\frac{1010}{1008.8-994}\)

= \(\frac{1010}{1008.7+1008-994}\)

= \(\frac{1010}{1008.7+14}\)

= \(\frac{1010}{1008.7+2.7}\)

= \(\frac{1010}{7\left(1008+2\right)}=\frac{1010}{7.1010}=\frac{1}{7}\)

D = \(\frac{1.2.3+2.4.6+3.6.9+5.10.15}{1.3.6+2.6.12+3.9.18+5.15.30}\)

= \(\frac{1.2.3+2.4.6+3.6.9+5.10.15}{1.3.2.3+2.6.4.3+3.9.6.3+5.15.10.3}\)

= \(\frac{1.2.3+2.4.6+3.6.9+5.10.15}{3\left(1.2.3+2.4.6+3.6.9+5.10.15\right)}=\frac{1}{3}\)

BCNN(7,3) = 21

\(\frac{1}{7}=\frac{1.3}{7.3}=\frac{3}{21}\)

\(\frac{1}{3}=\frac{1.7}{3.7}=\frac{7}{21}\)

C = \(\dfrac{1010}{1008\times8-994}\)

C = \(\dfrac{1010}{8064-994}\)

C = \(\dfrac{1010}{7070}\)

C = \(\dfrac{1}{7}\)

D = \(\dfrac{1.2.3+2.4.6+3.6.9+5.10.15}{1.3.6+2.6.12+3.9.18+5.15.30}\)

D = \(\dfrac{6+8.6+6.27+6.125}{18+18.8+18.27+18.125}\)

D = \(\dfrac{6.\left(1+8+27+125\right)}{18.\left(1+8+27+125\right)}\)

D = \(\dfrac{1}{3}\)

C = \(\dfrac{1}{7}\) = \(\dfrac{3}{21}\)

D = \(\dfrac{1}{3}\) = \(\dfrac{7}{21}\)

a)\(=\frac{1}{7}\)

b)\(=\frac{1}{3}\)

quy đồng \(\frac{1}{7}=\frac{3.1}{3.7}=\frac{3}{21}\)

\(\frac{1}{3}=\frac{7.1}{7.3}=\frac{7}{21}\)

\(\frac{3}{21}+\frac{7}{21}=\frac{9}{21}=\frac{3}{7}\)

C = \(\frac{1010}{\left(1010-2\right).8-994}\)

= \(\frac{1010}{1010.8-2.8-994}\)

=\(\frac{1010}{1010.\left(8-1\right)}\)

=\(\frac{1}{7}\)

D = \(\frac{1.2.3.\left(1+2^3+3^3+5^3\right)}{1.3.6.\left(1+2^3+3^3+5^3\right)}\)

= \(\frac{1}{3}\)

Quy đồng ta được 2 phân số là: \(\frac{3}{21};\frac{7}{21}\)

\(\frac{1.2.3+2.4.6+3.6.9+5.10.15}{1.3.6+2.6.12+3.9.18+5.15.30}\)

\(=\frac{1.2.3.\left(1+2+3+5\right)}{1.3.6.\left(1+2+3+5\right)}\)

\(=\frac{1.2.3.5}{1.3.6.5}\)

\(=\frac{1}{3}\)