đặt 6 ở tử làm thừa số chung và 8 ở mẫu làm thừa số chung.rút gọn ta được kq là 6/8=3/4

\(\frac{\frac{6}{7}-\frac{6}{9}+\frac{6}{11}-\frac{6}{13}}{\frac{8}{7}-\frac{8}{9}+\frac{8}{11}-\frac{8}{13}}\)

=\(\frac{6.\left(\frac{1}{7}-\frac{1}{9}+\frac{1}{11}-\frac{1}{13}\right)}{8.\left(\frac{1}{7}-\frac{1}{9}+\frac{1}{11}-\frac{1}{13}\right)}\)

=\(\frac{6}{8}\)

=\(\frac{3}{4}\)

có z ko tính đk s p hỏi

tính tử òi tính mẫu òi tính cả thế nhé 

ko biết thì hỏi
muốn giỏi phải hok

1/12 chứ cháu

Ta có : 

\(P=\frac{\frac{6}{8}+\frac{6}{10}+\frac{6}{14}+\frac{6}{26}}{\frac{11}{4}+\frac{11}{5}+\frac{11}{7}+\frac{11}{13}}\)

\(\Rightarrow P=\frac{\frac{3}{4}+\frac{3}{5}+\frac{3}{7}+\frac{3}{13}}{11\left(\frac{1}{4}+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}\right)}\)

\(\Rightarrow P=\frac{3\left(\frac{1}{4}+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}\right)}{11\left(\frac{1}{4}+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}\right)}\)

\(\Rightarrow P=\frac{3}{11}\)

Vậy \(P=\frac{3}{11}\)

\(P=\frac{\frac{3}{4}-\frac{3}{5}+\frac{3}{7}+\frac{3}{13}}{\frac{11}{4}-\frac{11}{5}+\frac{11}{7}+\frac{11}{13}}=\frac{3}{11}\)

đề bài của bn sai nên mk sửa luôn nha

a Đ

b S

c S

d Đ

a ) S 

b ) Đ

c ) S

d ) Đ

k cho mk nhé 

Mai Hồng Ngọc? Vũ Thị Thu Hằng? Ai đúng dzậy -_-*

Bài 1:

a) Ta có: \(\frac{8}{40}+\frac{-4}{20}-\frac{3}{5}\)

\(=\frac{1}{5}+\frac{-1}{5}-\frac{3}{5}\)

\(=\frac{-3}{5}\)

b) Ta có: \(\frac{-7}{12}+\frac{-2}{12}-\frac{-3}{36}\)

\(=\frac{-7}{12}+\frac{-2}{12}-\frac{-1}{12}\)

\(=\frac{-9+1}{12}=\frac{-8}{12}=\frac{-2}{3}\)

c) Ta có: \(\left(\frac{1}{6}+\frac{-4}{13}\right)-\left(-\frac{17}{6}-\frac{30}{13}\right)\)

\(=\frac{1}{6}+\frac{-4}{13}+\frac{17}{6}+\frac{30}{13}\)

\(=3+2=5\)

d) Ta có: \(-\frac{-5}{4}+\frac{7}{4}-\frac{-11}{7}+\frac{2}{7}\)

\(=\frac{5}{4}+\frac{7}{4}+\frac{11}{7}+\frac{2}{7}\)

\(=3+\frac{13}{7}=\frac{21}{7}+\frac{13}{7}=\frac{34}{7}\)

e) Ta có: \(-\frac{1}{8}+\frac{-7}{9}+\frac{-7}{8}+\frac{6}{7}+\frac{2}{14}\)

\(=-1+1+\frac{-7}{9}\)

\(=-\frac{7}{9}\)

f) Ta có: \(\frac{-2}{9}-\frac{11}{-9}+\frac{5}{7}-\frac{-6}{-7}\)

\(=\frac{-2-\left(-11\right)}{9}+\frac{5-6}{7}\)

\(=1+\frac{-1}{7}=\frac{7}{7}+\frac{-1}{7}=\frac{6}{7}\)

Tính :

a) \(\frac{1}{6}.\frac{9}{-8}.\left(-\frac{12}{11}\right)=\frac{1.9.\left(-12\right)}{6.\left(-8\right).11}=\frac{1.3.3}{2.2.11}=\frac{9}{44}\)

b) \(\frac{1}{8}.\frac{-3}{7}+\frac{1}{8}.\frac{-4}{7}\)

\(=\frac{1}{8}.\left(-\frac{3}{7}+\frac{-4}{7}\right)\)

\(=\frac{1}{8}.\frac{-7}{7}=\frac{1}{8}.\left(-1\right)\)

\(=-\frac{1}{8}\)

c) \(\frac{7}{13}.\frac{3}{-5}+\frac{6}{13}.\frac{-3}{5}\)

\(=-\frac{3}{5}.\left(\frac{7}{13}+\frac{6}{13}\right)\)

\(=-\frac{3}{5}.\frac{13}{13}=-\frac{3}{5}.1\)

\(=-\frac{3}{5}\)

a, \(\frac{1}{6}.\frac{9}{-8}.\frac{-12}{11}\)

\(\Rightarrow\frac{9}{8}.\frac{2}{11}\)

\(\Rightarrow\frac{9}{4}.\frac{1}{11}\)

\(\Rightarrow\frac{9}{44}\)

b,\(\frac{1}{8}.\frac{-3}{7}+\frac{1}{8}.\frac{-4}{7}\)

\(\Rightarrow\frac{-3}{56}-\frac{1}{2}.\frac{1}{7}\)

\(\Rightarrow\frac{-3}{56}-\frac{1}{2}.\frac{1}{7}\)

\(\Rightarrow\frac{-3}{56}-\frac{1}{14}\)

\(\Rightarrow\frac{-1}{8}\)

c,\(\frac{7}{13}.\frac{3}{-5}+\frac{6}{13}.\frac{-3}{5}\)

\(\Rightarrow\frac{-21}{65}-\frac{18}{65}\)

\(\Rightarrow\frac{-3}{5}\)

a, \(\frac{1}{6}.\frac{9}{-8}.\frac{-12}{11}\)

\(=\frac{1}{6}.\frac{-9}{8}.\frac{-12}{11}\)

\(=\frac{-3}{16}.\frac{-12}{11}\)

\(=\frac{9}{44}\)

b, \(\frac{1}{8}.\frac{-3}{7}+\frac{1}{8}.\frac{-4}{7}\)

\(=\frac{1}{8}.\left(\frac{-3}{7}+\frac{-4}{7}\right)\)

\(=\frac{1}{8}.\left(-1\right)\)

\(=\frac{-1}{8}\)

c, \(\frac{7}{13}.\frac{3}{-5}+\frac{6}{13}.\frac{-3}{5}\)

\(=\frac{7}{13}.\frac{-3}{5}+\frac{6}{13}.\frac{-3}{5}\)

\(=\frac{-3}{5}.\left(\frac{7}{13}+\frac{6}{13}\right)\)

\(=\frac{-3}{5}.1\)

\(=\frac{-3}{5}\)

giúp với ạ

giải dc nhưng mà hoi lâu

a)\(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\) ; \(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)

\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\); \(\dfrac{16}{25}-\dfrac{2}{5}=\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)