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

Câu 2:

a) \(-\frac{55}{132}=\frac{-55:11}{132:11}=-\frac{5}{12}\)

b) \(\frac{13.3^n}{6^m}=\frac{13.3^n}{2^m.3^m}=\frac{13}{2^m}.3^{n-m}\)

Câu 3:

a) Ta có: \(\frac{3}{14\ }>0;\ -\frac{6}{14}<0\)

nên \(\frac{3}{14}>-\frac{6}{14}\)

b) \(\frac{7}{-12}=\frac{-21}{36}\)

\(\frac{11}{-18}=\frac{-22}{36}\)

- 22 < - 21

=> \(\frac{7}{-12\ }>\frac{11}{-18}\)

Ta có:

Câu 4:

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

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

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

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

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

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