So sánh các phân số sau: 3/14 và - 6/14

Câu 4:

a) $\frac{5}{16}-\frac{5}{24}=\frac{15}{48}-\frac{10}{48}=\frac{5}{48}$

b) $-\frac{5}{8}+\frac{12}{7}+\frac{13}{8}+\frac{2}{7}=(-\frac{5}{8}+\frac{13}{8})+(\frac{12}{7}+\frac{2}{7})=1+2=3$

c) $\frac{2}{1.2}+\frac{2}{2.3}+\frac{2}{3.4}+...+\frac{2}{99.100}$

$=2(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100})$

$=2(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100})$

$=2(1-\frac{1}{100})=2.\frac{99}{100}=\frac{198}{100}$$=\frac{99}{50}$