\(70:\frac{4x+720}{x}=\frac{1}{2}\)

\(\frac{4x+720}{x}=70:\frac{1}{2}\)

\(\frac{4x+720}{x}=140\)

\(4x+720=140x\)

\(4x-140x=-720\)

\(-136x=-720\)

\(x=\frac{-720}{-136}\)

\(x=\frac{90}{17}\)

\(\frac{70x}{4x+720}=\frac{1}{2}\)

\(140x=4x+720\)

\(136x=720\)

        \(x=720:136\)

        \(x=\frac{90}{17}\)

\(70\div\frac{4x+720}{x}=\frac{1}{2}\)

=> \(70\cdot\frac{x}{4x+720}=\frac{1}{2}\)

=> \(\frac{70x}{4x+720}=\frac{1}{2}\)

=> \(70x\cdot2=4x+720\)

=> \(140x=4x+720\)

=> \(140x-4x=720\)

=> \(136x=720\)

=> \(x=\frac{720}{136}=\frac{90}{17}\)

\(\frac{11}{125}-\frac{17}{18}-\frac{5}{7}+\frac{4}{9}+\frac{17}{14}\)

\(=\frac{11}{125}-\left(\frac{17}{18}-\frac{8}{18}\right)+\left(\frac{17}{14}-\frac{10}{14}\right)\)

\(=\frac{11}{125}-\frac{1}{2}+\frac{1}{2}\)

\(=\frac{11}{125}+\left(\frac{1}{2}-\frac{1}{2}\right)\)= \(\frac{11}{125}\)

b) \(\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)

\(=\left(6-5-3\right)+\left(\frac{7}{3}-\frac{5}{3}-\frac{2}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)

\(=-2+0+\frac{-1}{2}\)

= \(-2-\frac{-1}{2}=-\left(2+\frac{1}{2}\right)=-2\frac{1}{2}\)

ấy chỗ b) thiếu bước đầu mở ngoặc r mới nhóm nhé :))

\(\left|x+\frac{4}{15}\right|-\left|-3.75\right|=-\left|-2,15\right|\)

\(\Rightarrow\left|x+\frac{4}{15}\right|-\frac{15}{4}=-\frac{43}{20}\)

\(\Rightarrow\left|x+\frac{4}{15}\right|=-\frac{43}{20}+\frac{15}{4}\)

\(\Rightarrow\left|x+\frac{4}{15}\right|=\frac{8}{5}\)

\(\Rightarrow\orbr{\begin{cases}x+\frac{4}{15}=\frac{8}{5}\\x+\frac{4}{15}=-\frac{8}{5}\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{4}{3}\\x=-\frac{28}{15}\end{cases}}\)

\(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\) 

\(\left|x+\frac{4}{15}\right|-3,75=-2,15\) 

\(\left|x+\frac{4}{15}\right|=1,6\) 

=>  \(x+\frac{4}{15}=1,6\)  hoặc  \(x+\frac{4}{15}=-1,6\) 

=>  \(x=\frac{4}{3}\) hoặc \(x=\frac{-28}{15}\) 

Vậy..

=> x + 4/15 - 3,75 = -2,15

=> x +4/15 =-2,15 + 3,75

=> x+4/15 = 1,6

=> x = 1,6-4/15

=> x = 4/3

trong câu hỏi tương tự có một bài giốngđè và được giải rồi, bạn xem thử đi

mh biết làm bài này rùi bn có cần mi2h đang cho bn ko?

a)\(\dfrac{11}{125}-\dfrac{17}{18}-\dfrac{5}{7}+\dfrac{4}{9}+\dfrac{17}{14}\)

\(=\dfrac{11}{125}-\left(\dfrac{17}{18}-\dfrac{4}{9}\right)-\left(\dfrac{5}{7}-\dfrac{17}{14}\right)\)

\(=\dfrac{11}{125}-\dfrac{5}{18}-\dfrac{-7}{14}=\dfrac{11}{125}-\dfrac{5}{18}+\dfrac{1}{2}\)

\(=\dfrac{11}{125}-\left(\dfrac{5}{18}-\dfrac{1}{2}\right)=\dfrac{11}{125}-\dfrac{-4}{18}=\dfrac{11}{125}+\dfrac{2}{9}\)

a)\(\frac{11}{125}-\frac{17}{18}-\frac{5}{7}+\frac{4}{9}+\frac{7}{14}\)

=\(\frac{11}{125}-\left(\frac{17}{18}-\frac{4}{9}\right)+\left(\frac{17}{14}-\frac{5}{7}\right)\)

=\(\frac{11}{125}-\frac{1}{2}+\frac{1}{2}\)

=\(\frac{11}{125}+\left(\frac{1}{2}-\frac{1}{2}\right)\)

=\(\frac{11}{125}\)

b)................................đề bài......................................................

=  ( 1 - 1 ) + ( 2 - 2 ) + ( 3 - 3 ) + ( -1/2 + -1/2 ) + ( -2/3 + -1/3) + ( -3/4 + -1/4) +  4

=       0     +     0     +      0      +         (-1)       +         (-1)      +         (-1)      + 4

=                                            1