Question

tính 
a)-5/6 + 3/-7
b)2/5 - 4/9
c)-6/5 x 4/7
d)2/3 : -4/5
mọi người giúp mình với

Answer 1

a:  =-5/6-3/7=-35/42-18/42=-53/42

b: =18/45-20/45=-2/45

c: =-24/35

d: =2/3x-5/4=-10/12=-5/6

Answer 2

\(\dfrac{-5}{6}+\dfrac{3}{7}=\dfrac{-5\times7+3\times6}{6\times7}=\dfrac{-17}{42}.\)

\(\dfrac{2}{5}-\dfrac{4}{9}=\dfrac{2\times9-4\times5}{5\times9}=\dfrac{-2}{45}.\)

\(\dfrac{-6}{5}\times\dfrac{4}{7}=\dfrac{-6\times4}{5\times7}=\dfrac{-24}{35}.\)

\(\dfrac{2}{3}:\dfrac{-4}{5}=\dfrac{2}{3}\times\dfrac{5}{-4}=\dfrac{-5}{6}.\)