51/30

24/65

chưa xong 

a, \(\frac{3}{5}+\frac{-4}{15}=\frac{9}{15}-\frac{4}{15}=\frac{5}{15}=\frac{1}{3}\)

b, \(\frac{-1}{3}+\frac{2}{5}+\frac{2}{15}=\frac{-5}{15}+\frac{6}{15}+\frac{2}{15}=\frac{3}{15}=\frac{1}{5}\)

c, \(\frac{-3}{5}+\frac{7}{21}+\frac{-4}{5}+\frac{7}{5}=\frac{-3}{5}+\frac{1}{3}+\frac{-4}{5}+\frac{7}{5}=\left(\frac{-3}{5}+\frac{-4}{5}+\frac{7}{5}\right)+\frac{1}{3}=\frac{1}{3}\)

d, \(\frac{2}{7}+\frac{1}{9}+\frac{3}{7}+\frac{5}{9}+\frac{-5}{6}=\left(\frac{2}{7}+\frac{3}{7}\right)+\left(\frac{1}{9}+\frac{5}{9}\right)+\frac{-5}{6}=\frac{5}{7}+\frac{6}{9}+\frac{-5}{6}=\frac{90}{126}+\frac{84}{126}+\frac{-105}{126}=\frac{69}{126}=\frac{23}{42}\)

e, \(\frac{-5}{7}+\frac{3}{4}+\frac{-1}{5}+\frac{-2}{7}+\frac{1}{4}=\left(\frac{-5}{7}+\frac{-2}{7}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)+\frac{-1}{5}=\left(-1\right)+1+\frac{-1}{5}=\frac{-1}{5}\)

f, \(\frac{-3}{31}+\frac{-6}{17}+\frac{1}{25}+\frac{-28}{31}+\frac{-1}{17}+\frac{-1}{5}=\left(\frac{-3}{31}+\frac{-28}{31}\right)+\left(\frac{-6}{17}+\frac{-1}{17}\right)+\left(\frac{1}{25}+\frac{-1}{5}\right)=\left(-1\right)+\frac{-7}{17}+\frac{-4}{25}=\frac{-425}{425}+\frac{-175}{425}+\frac{-68}{425}=\frac{-668}{425}\)

Chúc bn học tốt

hi {\___/}

(^__^)

>like>

ngu thế

làm hộ tớ  nhé

ngu the  xcuiegudg

sao chửi người ta ngu có khi còn ngu hơn người ta nữa ở đó mà lên giọng

bn có thể ghi rõ ra ko ,mk ko hiểi

lag mắt quá, chế ơi!

4/7x9/5-3/7+4/7:5/6+6/7x2

=36/35-3/7+24/35+12/7

=36/35-15/35+24/35+60/35

=21/35+24/35+60/35

=45/35+60/35

=105/35

=3

gõ đề bằng công thức toán nếu muốn đc trợ giúp tốt nhất

a, \(\dfrac{x-2}{5}=\dfrac{5}{7}\)

\(\Rightarrow7\left(x-2\right)=25\Rightarrow7x-14=25\)

\(\Rightarrow7x=39\Rightarrow x=\dfrac{39}{7}\)

b, \(\dfrac{-x-2}{3}=\dfrac{-6}{7}\)

\(\Rightarrow7\left(-x-2\right)=-18\Rightarrow-7x-14=-18\)

\(\Rightarrow-7x=-4\Rightarrow x=\dfrac{4}{7}\)

c, \(\dfrac{4}{7-x}=\dfrac{1}{3}\)

\(\Rightarrow12=7-x\Rightarrow7-x=12\)

\(\Rightarrow x=7-12=-5\)

Chúc bạn học tốt!!!

a, \(\dfrac{x-2}{5}=\dfrac{5}{7}\)

\(\Rightarrow7\left(x-2\right)=5^2\)

\(\Rightarrow7x-14=25\)

\(\Rightarrow7x=39\)

\(\Rightarrow x=\dfrac{39}{7}\)

b, \(\dfrac{-x-2}{3}=\dfrac{-6}{7}\)

\(\Rightarrow7\left(-x-2\right)=-6.3\)

\(\Rightarrow-7x-2=-18\)

\(\Rightarrow-7x=-16\)

\(\Rightarrow x=\dfrac{16}{7}\)

c, \(\dfrac{4}{7-x}=\dfrac{1}{3}\)

\(\Rightarrow7-x=4.3=12\)

\(\Rightarrow x=-5\)

a,  \(\dfrac{-3}{5}+\dfrac{5}{7}\)

\(=\dfrac{4}{35}\)

b, \(-5+\dfrac{1}{6}\)

= \(\dfrac{-29}{6}\)

c, \(\dfrac{1}{8}-\dfrac{1}{2}\)

= \(\dfrac{-3}{8}\)

c, \(\dfrac{5}{12}-\dfrac{-7}{6}\)

= \(\dfrac{19}{12}\)

d, \(-2.\dfrac{3}{7}\)

= \(\dfrac{-6}{7}\)