a, \(\dfrac{11}{13}-\left(\dfrac{5}{42}-x\right)=-\left(\dfrac{15}{28}-\dfrac{11}{13}\right)\)

\(\Rightarrow\dfrac{11}{13}-\dfrac{5}{42}+x=\dfrac{-15}{28}+\dfrac{11}{13}\)

\(\Rightarrow x=\dfrac{-15}{28}+\dfrac{11}{13}-\dfrac{11}{13}+\dfrac{5}{42}\)

\(\Rightarrow x=\dfrac{-5}{12}\)

Vậy....

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

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

\(\Rightarrow\left|x+\dfrac{4}{15}\right|=1,6\)

\(\Rightarrow\left\{{}\begin{matrix}x+\dfrac{4}{15}=1,6\\x+\dfrac{4}{15}=-1,6\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{4}{3}\\x=-\dfrac{28}{15}\end{matrix}\right.\)

Vậy.....

Chúc bạn học tốt!!!

a)

\(\dfrac{11}{13}-\left(\dfrac{5}{42}-x\right)=-\left(\dfrac{15}{28}-\dfrac{11}{13}\right)\)

\(\Leftrightarrow\dfrac{11}{13}-\dfrac{5}{42}+x=\dfrac{113}{364}\Leftrightarrow x=\dfrac{113}{364}+\dfrac{5}{42}-\dfrac{11}{13}=-\dfrac{5}{12}\)

b)

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

\(\Leftrightarrow\left|x+\dfrac{4}{15}\right|-3,75=-2,15\Leftrightarrow\left|x+\dfrac{4}{15}\right|=1,6\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{4}{15}=1,6\\x+\dfrac{4}{15}=-1,6\end{matrix}\right.\)\(\Leftrightarrow x\in\left\{\dfrac{4}{3};-\dfrac{28}{15}\right\}\)

x : 4 + x = 3,75

x : ( 4-1 ) = 3,75

x : 3 = 3,75

x = 3,75 x 3

x= 11,25

X x1/4 + X = 3,75 

X x ( 1 + 1/4 ) = 3,75

X x 1/1/4 = 3,75

X x 1,25 = 3,75

X           = 3,75 : 1,25

X           =3

x : 4 + x = 3,75

x : ( 4-1 ) = 3,75

x : 3 = 3,75

x = 3,75 x 3

x= 11,25

a: \(\left|x+\dfrac{4}{15}\right|-\left|-3.75\right|=-\left|-2.5\right|\)

\(\Leftrightarrow\left|x+\dfrac{4}{15}\right|=-2.5+3.75=1.25=\dfrac{5}{4}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{4}{15}=\dfrac{5}{4}\\x+\dfrac{4}{15}=-\dfrac{5}{4}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{59}{60}\\x=-\dfrac{91}{60}\end{matrix}\right.\)

c: \(\left|x-y\right|+\left|y+\dfrac{9}{25}\right|=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x-y=0\\y+\dfrac{9}{25}=0\end{matrix}\right.\Leftrightarrow x=y=-\dfrac{9}{25}\)

d: Ta có: \(\left|x\left(x^2-\dfrac{5}{4}\right)\right|=x\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\x\left(x^2-\dfrac{5}{4}\right)=x\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>=0\\x\left(x^2-\dfrac{9}{4}\right)=0\end{matrix}\right.\Leftrightarrow x\in\left\{0;\dfrac{3}{2}\right\}\)

3,75:x=5,25-3,75

3,75:x=1,5

x=2,5

5,25-3,75:x=3,75

3,75:x=5,25-3,75=1,5

x=2,5

\(5,25-3,75\div x=3,75\)
\(3,75\div x=5,25-3,75\)
\(3,75\div x=1,5\)
\(x=3,75\div1,5\)
\(x=2,5\)
Tích nha! 

=2.25*\(\left(0.5+2\right)\)+3.75

=2.25*2.5+3.75

=5.625+3.75

=5.7

kết quả là 3

x/4+x=3.75

x=3.75-3/4

x=3.75-0.75

x= 3 

viết rõ đề dùm cái

\(\frac{x}{4}+x=3,75\)

\(x\times0,25+x=3,75\)

\(x\times\left(1+0,25\right)=3,75\)

\(x\times1,25=3,75\)

\(x=3,75:1,25\)

\(x=3\)

96 - 3. 75: x= 94,5

96 - 225: x= 945\10

96- 225: x= 189\2

225: x= 96- 189\2

225:x=192\2-189\2

225:x=3\2

x=225:3\2

X=225.2\3

x=150

96 - 3. 75: x= 94,5

96 - 225: x= 945\10

96- 225: x= 189\2

225: x= 96- 189\2

225:x=192\2-189\2

225:x=3\2

x=225:3\2

X=225.2\3

x=150

96 - 3. 75: x= 94,5

96 - 225: x= 945\10

96- 225: x= 189\2

225: x= 96- 189\2

225:x=192\2-189\2

225:x=3\2

x=225:3\2

X=225.2\3

x=150

fan vu liz 

= 3.75 * (6.8 - 6.8)

= 3.75 * 0

= 0

3.75*6.8-6.8*3.75

= 6,8 x ( 3,75 - 3,75 )

= 6,8 x 0

= 6,8