\(\frac{15^3.8^2}{5^6.4^4}=\frac{\left(3.5\right)^3.\left(2^3\right)^2}{5^6.\left(2^2\right)^4}=\frac{3^3.5^3.2^6}{5^6.2^8}=\frac{3^3}{5^3.2^2}=\frac{27}{500}\)

\(=\dfrac{-1.3^2.7.8}{7.2}=-18\)

\(=\dfrac{\left(-2\right)^2.\left(-2\right).9.9.9.5^2.5^2.5.7.8}{3^2.3^2.3^2.4.4^2.25.25.25.14}=\dfrac{-2.5.7.8}{4^2.14}=\dfrac{-560}{224}=\dfrac{-5}{2}\)

\(\dfrac{\left(-2\right)^3.9^3.5^5.7.8}{3^6.4^4.25^3.14}=-\dfrac{2^3.\left(3^2\right)^3.5^5.7.2^3}{3^6.\left(2^2\right)^4.\left(5^2\right)^3.7.2}=-\dfrac{2^6.3^6.5^5.7}{2^9.3^6.5^6.7}=-\dfrac{1}{2^3.5}=-\dfrac{1}{40}\)

\(\frac{6.4+6.7}{6.5+12}=\frac{4+1.7}{1.5+2}=\frac{4+7}{5+2}=\frac{11}{7}\)

\(\frac{6\cdot4+6\cdot7}{6\cdot5+12}\)

\(=\frac{6\left(4+7\right)}{6\cdot5+6\cdot2}\)

\(=\frac{6\left(4+7\right)}{6\left(5+2\right)}\)

\(=\frac{11}{7}\)

\(\frac{9}{6}.\frac{6}{7}+\frac{9}{6}.\frac{4}{5}\)

\(=\frac{9}{6}\left(\frac{6}{7}+\frac{4}{5}\right)\)

\(=\frac{9}{6}\left(\frac{30}{35}+\frac{28}{35}\right)\)

\(=\frac{3}{2}.\frac{58}{35}\)

\(=\frac{174}{70}\)

\(=\frac{87}{35}\)

a/\(\frac{3939-101}{3.2929+505}=\frac{39.101-101}{8787+505}=\frac{101.\left(39-1\right)}{87.101+5.101}=\frac{101.38}{101.\left(87+5\right)}=\frac{38}{92}\)

\(=\frac{38}{92}\)

b/\(\frac{6.4+6.7}{6.5+12}=\frac{4+1.7}{1.5+2}=\frac{4+7}{5+2}=\frac{11}{7}\)

\(\frac{6.4+6.7}{6.5+12}\)\(=\frac{6.4+6.7}{6.5+6.2}\)\(=\frac{6.\left(4+7\right)}{6.\left(5+2\right)}\)\(=\frac{6.11}{6.7}\)\(=\frac{11}{7}\)

1: Rút gọn

a) \(-\dfrac{33}{51}=\dfrac{-33:3}{51:3}=\dfrac{-11}{17}\)

b) \(\dfrac{156}{-168}=\dfrac{-156}{168}=\dfrac{-156:12}{168:12}=\dfrac{-13}{14}\)

c) \(\dfrac{-75}{-100}=\dfrac{75}{100}=\dfrac{75:25}{100:25}=\dfrac{3}{4}\)

2: Quy đồng mẫu:

a) \(-\dfrac{3}{8}\) và \(\dfrac{5}{4}\)

MSC: 8

\(-\dfrac{3}{8}=\dfrac{-3}{8}\)

\(\dfrac{5}{4}=\dfrac{5\cdot2}{4\cdot2}=\dfrac{10}{8}\)

b) \(\dfrac{-7}{6}\) ; \(\dfrac{5}{12}\) và \(-\dfrac{5}{6}\)

MSC: 12

\(-\dfrac{7}{6}=\dfrac{-7\cdot2}{6\cdot2}=\dfrac{-14}{12}\)

\(\dfrac{5}{12}=\dfrac{5}{12}\)

\(\dfrac{-5}{6}=\dfrac{-5\cdot2}{6\cdot2}=\dfrac{-10}{12}\)

\(\frac{6^5+6^6.7}{6^3+6^6.4}=\frac{6^5.\left(1+6.7\right)}{6^3.\left(1+6^3.4\right)}\)

\(=\frac{6^2.43}{865}=\frac{36.43}{865}\)

\(=\frac{1568}{865}\)

Bài 1: \(49+7\cdot\frac{49}{49}=49+7\cdot1\)

\(=49+7=56\)

Bài 2: \(\frac{1}{3}:0,25+\frac{7}{6}\cdot\frac{4}{7}-60=\frac{1}{3}:\frac{1}{4}+\frac{7\cdot4}{6\cdot7}-60\)

\(=\frac{1}{3}\cdot\frac{4}{1}+\frac{4}{6}-60=\frac{4}{3}+\frac{2}{3}-60\)

\(=\frac{6}{3}-60=2-60=-58\)

cảm ơn bạn Phạm Trà Giang nhiều nha, nhưng bài 2 mik thấy đổi 0,25 thành phân số là bằng 1/4 mà bạn thử kiểm tra lại kết quả nhé!!! Mik ẫn cảm ơn bạn nhiều nha.

= 2/7 

= 33/8 

nha bn nguyen tuan anh

\(\frac{48}{168}\cdot\frac{132}{32}=\frac{2^4\cdot3}{2^3\cdot3\cdot7}\cdot\frac{2^2\cdot3\cdot11}{2^5}=\frac{2\cdot1}{1\cdot1\cdot7}\cdot\frac{1\cdot3\cdot11}{2^3}=\frac{33}{28}\)