a)tích chéo

b);c);d)Chuyển 2 vế thành phân số rồi tích chéo

a ) \(\left(-\frac{40}{52}.0,32.\frac{17}{20}\right):\frac{64}{75}\)

= \(\left(-\frac{16}{65}.\frac{17}{20}\right):\frac{64}{75}\)

= \(\left(-\frac{68}{325}\right):\frac{64}{75}\)

= \(\frac{-51}{208}\)

b ) \(-\frac{10}{11}.\frac{8}{9}+\frac{7}{18}.\frac{10}{11}\)

= \(\frac{10}{11}.\left(-\frac{8}{9}+\frac{7}{18}\right)\)

= \(\frac{10}{11}.\left(-\frac{1}{2}\right)\)

= \(\frac{-5}{11}\)

c ) \(\frac{45^{10}.5^{20}}{75^{15}}\)

= \(\frac{5^{10}.3^{20}.5^{20}}{5^{30}.3^{15}}\)

= \(\frac{5^{30}.3^{20}}{5^{30}.3^{15}}\)

= 3 ⁵

= 243

d ) ( - 0,125 ) ³ . 80 ⁴

= -80000

lớp 5 cũng có thể làm bài toán này

bạn suy nghĩ đi

dễ ợt à

tíc mình nha

minh ánh ơi giúp mình với 

A = \(\left(\frac{1}{15}-\frac{1}{15}\right)\)\(+\left(\frac{3}{7}-\frac{3}{7}\right)\)\(+\left(\frac{5}{9}-\frac{5}{9}\right)\)\(+\left(\frac{2}{11}-\frac{2}{11}\right)\)\(+\left(\frac{7}{13}-\frac{7}{13}\right)\)\(-\frac{9}{16}\)

A = 0 + 0 + 0 + 0 + 0 - \(\frac{9}{16}\)

A = \(-\frac{9}{16}\)

\(A=\frac{1}{5}-\frac{3}{7}+\frac{5}{9}-\frac{2}{11}+\frac{7}{13}-\frac{9}{16}-\frac{7}{13}+\frac{2}{11}-\frac{5}{9}+\frac{3}{7}-\frac{1}{5}\)

     \(=\left(\frac{1}{5}-\frac{1}{5}\right)-\left(\frac{3}{7}-\frac{3}{7}\right)+\left(\frac{5}{9}-\frac{5}{9}\right)-\left(\frac{2}{11}-\frac{2}{11}\right)+\left(\frac{7}{13}-\frac{7}{13}\right)-\frac{9}{16}\)

     \(=0-0+0-0+0-\frac{9}{16}\)

    \(=-\frac{9}{16}\)

B. 1/3 - 1/3 - 3/5 +3/5 + 5/7 - 5/7  + 9/11 - 9/11 -11/13 + 11/ 13 + 7/9 + 13/15

= 0 -0-0-0-0+7/9 +13/15

= 74/45

b, Nhóm các cặp trái dấu vào với nhau thì hết cuối cùng còn 13/15

c,\(\frac{1}{99}-\frac{1}{99}+\frac{1}{98}-\frac{1}{98}+...+\frac{1}{2}-\frac{1}{3}+1\)

= \(\frac{1}{6}+1\)= 7/6

1.a) Sửa lại đề: \(\frac{11}{17}\)ở mẫu chuyển thành \(\frac{11}{7}\)

\(\frac{0,75+0,6-\frac{3}{7}-\frac{3}{13}}{2,75+2,2-\frac{11}{7}-\frac{11}{13}}=\frac{\frac{3}{4}+\frac{3}{5}-\frac{3}{7}-\frac{3}{13}}{\frac{11}{4}+\frac{11}{5}-\frac{11}{7}-\frac{11}{13}}\)\(=\frac{3\left(\frac{1}{4}+\frac{1}{5}-\frac{1}{7}-\frac{1}{13}\right)}{11\left(\frac{1}{4}+\frac{1}{5}-\frac{1}{7}-\frac{1}{13}\right)}=\frac{3}{11}\)

( vì \(\frac{1}{4}+\frac{1}{5}-\frac{1}{7}-\frac{1}{13}\ne0\))

2.a) \(\frac{3}{5}+\frac{3}{2}.x=\frac{-5}{7}\)\(\Leftrightarrow\frac{3}{2}.x=\frac{-5}{7}-\frac{3}{5}\)

\(\Leftrightarrow\frac{3}{2}.x=\frac{-46}{35}\)\(\Leftrightarrow x=\frac{-46}{35}:\frac{3}{2}\)\(\Leftrightarrow x=\frac{-92}{105}\)

Vậy \(x=\frac{-92}{105}\)

b) \(\left(4x-\frac{1}{3}\right).\left(\frac{3}{2}x+\frac{5}{6}\right)=0\)\(\Leftrightarrow\orbr{\begin{cases}4x-\frac{1}{3}=0\\\frac{3}{2}x+\frac{5}{6}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}4x=\frac{1}{3}\\\frac{3}{2}x=\frac{-5}{6}\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{12}\\x=\frac{-5}{9}\end{cases}}\)

Vậy \(x=\frac{-5}{9}\)hoặc \(x=\frac{1}{12}\)

a)              75 - 3.(2/13+1/17-1/19)            3.[25-(2/13+1/17-1/19)]

               -------------------------------------- = ---------------------------------------------- = 3/11

                275-11.(2/13+1/17-1/19)            11.[25-(2/13+1/17-1/19)]

a)     \(\frac{75-\frac{6}{13}+\frac{3}{17}-\frac{3}{19}}{275-\frac{22}{13}+\frac{11}{17}-\frac{11}{19}}=\frac{75-3.\left(\frac{2}{13}+\frac{1}{17}-\frac{1}{19}\right)}{275-11.\left(\frac{2}{13}+\frac{1}{17}-\frac{1}{19}\right)}\)

                                                         \(=\frac{75-3}{275-11}\)

                                                         \(=\frac{72}{264}=\frac{3}{11}\)

b)          \(\frac{2}{3.5}+\frac{7}{5.12}+\frac{9}{4.39}=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{12}+\frac{3}{52}\)

                                                        \(=\frac{1}{3}-\frac{1}{12}+\frac{3}{52}\)

                                                       \(=\frac{1}{4}+\frac{3}{52}=\frac{4}{13}\)

a) \(\frac{1}{12}+\frac{3}{15}+\frac{11}{12}+\frac{1}{71}-\frac{12}{10}=\left(\frac{1}{12}+\frac{11}{12}\right)+\left(\frac{1}{5}-\frac{1}{5}\right)+\frac{1}{71}\)

\(=\frac{12}{12}+0+\frac{1}{71}=1+\frac{1}{71}=1\frac{1}{71}=\frac{72}{71}\)

b) \(\frac{2}{3}-4\left(\frac{1}{2}+\frac{3}{4}\right)=\frac{2}{3}-4.\frac{5}{4}=\frac{2}{3}-5=\frac{2}{3}-\frac{15}{3}=-\frac{13}{3}\)

c) \(\frac{-4}{13}.\frac{3}{17}+\frac{-12}{13}.\frac{4}{7}+\frac{4}{13}=\frac{4}{13}.\frac{-3}{17}+\frac{4}{13}.\frac{-12}{17}+\frac{4}{13}.1\)

\(=\frac{4}{13}\left(\frac{-3}{17}+\frac{-12}{17}+1\right)=\frac{4}{13}\left(\frac{-15}{17}+\frac{17}{17}\right)=\frac{4}{13}.\frac{2}{17}=\frac{8}{221}\)

d) \(\frac{10^3+2.5+5^3}{55}=\frac{1000+10+125}{55}=\frac{1135}{55}=\frac{227}{11}\)