_17*13+17\(\frac{-17\cdot13+17\cdot2}{11\cdot2-11\cdot19}=\frac{-221+34}{22-209}=\frac{-187}{-187}=\frac{1}{1}=1\)

a. -1100/9

b. -3452/11

\(\frac{3.7.8.13}{14\cdot15\cdot26}=\frac{3\cdot7\cdot8\cdot13}{2\cdot7\cdot3\cdot5\cdot2\cdot13}=\frac{8}{5\cdot2\cdot2}=\frac{8}{20}=\frac{2}{5}\)

\(\frac{3.7.8.13}{14.15.26}=\frac{3.7.2^3.13}{2.7.3.5.13.2}=\frac{1.7.2.1}{1.1.1.5.1.1}=\frac{14}{5}\)

\(\frac{11.8-11.3}{17-6}=\frac{11.\left(8-3\right)}{11}=\frac{11.5}{11}=\frac{1.5}{1}=\frac{5}{1}=5\)

\(\frac{-17.13+17.2}{11.2-11.9}=\frac{-17.13+\left(-17\right).2}{11.\left(2-9\right)}=\frac{-17.\left(-13+2\right)}{11.\left(-7\right)}=\frac{-17.\left(-11\right)}{11.\left(-7\right)}=\frac{-17.\left(-1\right)}{-1.\left(-7\right)}=\frac{17}{7}\)

\(\frac{7}{9.10^2-2.10^2}=\frac{7}{100\left(9-2\right)}=\frac{7}{100.7}=\frac{7}{700}=\frac{1}{100}\)

mình làm được tới đó thôi, hihi. 

a ) 7. b ) − 1 c ) − 1 2

d ) 1 4 e ) − 1 7 f ) 17 21

Bài 14 : 

a. 55/66 = 55 : 11/66 : 11 = 5/6          b. -33/88 = -33 : 11/88 : 11 = -3/8        c. 2020/8080 = 2020 : 2020/8080 : 2020 = 1/4      

d. 2121/-4242 = 2121 : (-101)/(-4242) : (-101) = 21/42 = 1/2     

e. 130130/-260260 = 130130 : (-1001)/(-260260) : ( -1001 ) = -130/260 = -1/2

f. 1616/-1313 = 1616 : (-101)/(-1313) : (-101 ) = -16/13

 Chúc bạn học tốt nha !

Bài 14 khá đơn giản nên mình sẽ bỏ qua, bạn tự làm đc mà xD

15. a) \(\frac{13\cdot9-13\cdot2}{25-12}=\frac{13\left(9-2\right)̸}{13}=7\)

b) \(\frac{42-14\cdot8}{7+21\cdot3}=\frac{14\cdot3-14\cdot8}{7+63}=\frac{14\left(3-8\right)}{70}=\frac{14\cdot\left(-5\right)}{70}=\frac{-70}{70}=-1\)

c) \(\frac{9\cdot6-18\cdot4}{12\cdot3}=\frac{\left(9\cdot2\right)\cdot\left(6:2\right)-18\cdot4}{36}=\frac{18\cdot3-18\cdot4}{36}=\frac{18\left(3-4\right)}{36}=\frac{-18}{36}=\frac{-1}{2}\)

d) \(\frac{5\cdot5^2}{9\cdot10^2-4\cdot10^2}=\frac{5\cdot5^2}{10^2\left(9-4\right)}=\frac{5\cdot5^2}{10^2\cdot5}=\frac{1}{2^2}=\frac{1}{4}\)

e) \(\frac{\left(-7\right)\cdot3-4\cdot\left(-6\right)}{\left(-5\right)\cdot3-2\cdot3}=\frac{-21+24}{-15-6}=\frac{3}{-21}=\frac{-1}{7}\)

f) \(\frac{\left(-17\right)\cdot13+17\cdot2}{-11\cdot2-11\cdot19}=\frac{-\left[17\cdot\left(13+2\right)\right]}{-\left[11\cdot\left(2-19\right)\right]}=\frac{-17\cdot13-\left(-17\right)\cdot2}{-11\cdot2+\left(-11\right)\cdot19}=\frac{-17\left(13-2\right)}{-11\left(2+19\right)}=\frac{-17\cdot11}{-11\cdot19}=\frac{-17}{-19}=\frac{17}{19}\)

* Hơi dài xD , mong bạn thông cảm *

=3/17(13/15+2/15)=3/17

\(\dfrac{3}{17}\left(\dfrac{13}{15}+\dfrac{2}{15}\right)=\dfrac{3}{17}\times\dfrac{15}{15}=\dfrac{3}{17}\times1=\dfrac{3}{17}\)

a)  5

b)  1

\(\frac{27}{62}\)