a) \(\frac{-34}{37}\)\(\times\frac{74}{-85}\)\(\frac{-34}{37}\times\frac{74}{-85}=\frac{-34\times74}{37\times\left(-85\right)}=\frac{-34\times2}{1\times\left(-85\right)}=\frac{34}{85}\)     

b) \(\frac{-5}{9}:\frac{-7}{18}=\frac{-5}{9}\times\frac{-18}{7}=\frac{-4\times\left(-18\right)}{9\times7}=\frac{-4\times\left(-2\right)}{1\times7}=\frac{8}{7}\)

h cho minh nha 

a= -7/156

b=1/12

c=-7/55

d=17/21

e=10/7

cho minh nhé

\(\frac{-1}{39}+\frac{-1}{52}=\frac{-7}{156}\)

\(\frac{-6}{9}+\frac{12}{16}=\frac{-2}{3}+\frac{3}{4}=\frac{1}{12}\)

\(\frac{-2}{5}-\frac{-3}{11}-\frac{34}{37}-\frac{74}{-85}=\frac{-1215}{6919}\)

\(\frac{-5}{9}:\frac{-7}{18}=\frac{-5}{9}.\frac{-18}{7}=\frac{10}{7}\)

bấm mt

-1/39 + -1/52 = -7/156

-6/9 + -12/16 = -17/12

-2/5 - - 3/11 [ (-) + ( -) = +] = -2/5 + 3/11 = -7/55

-34/37 - 74/ -85 = -152/3145

-5/9 : -7/18 = 10/7

 -7/156

-17/12

-7/55

-152/3145

10/7

Quy đồng rồi tính là ra ngay mà

a) \(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-4}{156}+\dfrac{-3}{156}=\dfrac{-7}{156}\)

b) \(\dfrac{-6}{9}+\dfrac{-12}{16}=\dfrac{-2}{3}+\dfrac{-3}{4}=\dfrac{-8}{12}+\dfrac{-9}{12}=\dfrac{-17}{12}\)

c) \(\dfrac{-2}{5}-\dfrac{-3}{11}=\dfrac{-22}{55}-\dfrac{-15}{55}=\dfrac{-7}{55}\)

d) \(\dfrac{-34}{37}.\dfrac{74}{-85}=\dfrac{4}{5}\)

e) \(\dfrac{-5}{9}:\dfrac{-7}{18}=\dfrac{-5}{9}.\dfrac{18}{-7}=\dfrac{10}{7}\)

\(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-7}{156}\)

\(\dfrac{-6}{9}+\dfrac{-12}{16}=\dfrac{-17}{12}\)

\(\dfrac{-2}{5}-\dfrac{-3}{11}=\dfrac{-7}{55}\)

\(\dfrac{-34}{37}.\dfrac{74}{-85}=\dfrac{4}{5}\)

\(\dfrac{-5}{9}:\dfrac{-7}{18}=\dfrac{10}{7}\)

Chúc bạn học tốt!!!

a) \(\left(-\dfrac{1}{39}\right)+\left(-\dfrac{1}{52}\right)=\dfrac{-4-3}{156}=-\dfrac{7}{156}\)

b) \(\left(-\dfrac{6}{9}\right)+\left(-\dfrac{12}{16}\right)=-\dfrac{6}{9}-\dfrac{12}{16}=-\dfrac{17}{12}\)

c) \(-\dfrac{2}{5}-\left(-\dfrac{3}{11}\right)=-\dfrac{2}{5}+\dfrac{3}{11}=-\dfrac{7}{55}\)

d) \(\left(-\dfrac{34}{37}\right)\cdot\left(-\dfrac{74}{85}\right)=2\cdot\dfrac{2}{5}=\dfrac{4}{5}\)

e) \(\left(-\dfrac{5}{9}\right):\left(-\dfrac{7}{18}\right)=\dfrac{5}{9}\cdot\dfrac{18}{7}=5\cdot\dfrac{2}{7}=\dfrac{10}{7}\)

Ta có:\(-\frac{34}{37}.\frac{74}{-85}=\frac{\left(-34\right).74}{37.\left(-85\right)}=\frac{\left(-17\right).2.2.37}{37.\left(-17\right).5}=\frac{4}{5}\)

-34/37 x 74/-85

= -34x74 / 37x(-85)

Vì 2 số âm nhân với nhau nên kết quả là dương

= 34x74 / 37x85

= 17x2x37x2 / 37x17x5

= 4/5