Question

 

Rút gọn rồi qui đồng mẫu các phân số sau

C=1010/1008.8-994

D=1.2.3+2.4.6+3.6.9+5.10.15/1.3.6+2.6.12+3.9.18+5.15.30

Answer 1

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

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

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