Thế mày làm đi

cho ít thôi thì làm

623/12

1/15

5/12

2/7

4/15

1/4

=1/4

c) \(\left|x\right|=3,5\Rightarrow\left[{}\begin{matrix}x=3,5\\x=-3,5\end{matrix}\right.\)

d) \(\left|x\right|=-2,7\Rightarrow x\in\varnothing\) 

l) \(\left|x+\dfrac{3}{4}\right|-5=-2\Rightarrow\left|x+\dfrac{3}{4}\right|=3\)

\(\Rightarrow\left[{}\begin{matrix}x+\dfrac{3}{4}=3\\x+\dfrac{3}{4}=-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=3-\dfrac{3}{4}\\x=-3-\dfrac{3}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{9}{4}\\x=\dfrac{15}{4}\end{matrix}\right.\)

Đính chính câu l \(x=-\dfrac{15}{4}\) không phải \(x=\dfrac{15}{4}\)

n) Theo bài ra ta có: \(\frac{x+1}{2008}=\frac{502}{x+1}\)

=> (x+1).(x+1) = 2008.502

=> (x+1)² = 1008016

=> (x+1)² = 1004²

=> x+1 = 1004

=> x = 2004-1

=> x = 2003

Vậy x = 2003

p) Theo bà ra ta có: \(\left|\frac{5}{4}.x-\frac{7}{2}\right|-\left|\frac{5}{8}.x+\frac{3}{5}\right|=0\)

=> \(\left|\frac{5}{4}.x-\frac{7}{2}\right|=\left|\frac{5}{8}.x+\frac{3}{5}\right|\)

=> \(\frac{5}{4}.x-\frac{7}{2}=\pm\left(\frac{5}{8}.x+\frac{3}{5}\right)\)

=> \(\left[\begin{array}{nghiempt}\frac{5}{4}.x-\frac{7}{2}=\frac{5}{8}.x+\frac{3}{5}\\\frac{5}{4}.x-\frac{7}{2}=\frac{-5}{8}.x-\frac{3}{5}\end{array}\right.\)

=> \(\left[\begin{array}{nghiempt}\frac{5}{4}.x-\frac{5}{8}.x=\frac{3}{5}+\frac{7}{2}\\\frac{5}{4}.x+\frac{5}{8}.x=\frac{-3}{5}+\frac{7}{2}\end{array}\right.\)

=> \(\left[\begin{array}{nghiempt}\frac{5}{8}.x=\frac{41}{10}\\\frac{15}{8}.x=\frac{29}{10}\end{array}\right.\)

=> \(\left[\begin{array}{nghiempt}x=\frac{164}{25}\\x=\frac{116}{75}\end{array}\right.\)

Vậy x=\(\frac{164}{25}\) hoặc x=\(\frac{116}{75}\)

Dễ mà!

\(\frac{x+1}{2008}\)=\(\frac{502}{x+1}\)

=>(x+1)²=502.2008=1008016

=>(x+1)=1004  => x=1004-1=1003

Vậy x=1003

a: \(x-\frac13x+\frac15x=-\frac{26}{5}\)

=>\(x\left(1-\frac13+\frac15\right)=-\frac{26}{5}\)

=>\(x\left(\frac23+\frac15\right)=-\frac{26}{5}\)

=>\(x\cdot\left(\frac{10}{15}+\frac{3}{15}\right)=-\frac{26}{5}\)

=>\(x\cdot\frac{13}{15}=-\frac{26}{5}\)

=>\(x=-\frac{26}{5}:\frac{13}{15}=-\frac{26}{5}\cdot\frac{15}{13}=-2\cdot3=-6\)

b: \(\frac23\left(x+\frac95\right)-\frac{3}{10}\left(5x-\frac13\right)=\frac{7}{15}\)

=>\(\frac23x+\frac{18}{15}-\frac32x+\frac{1}{10}=\frac{7}{15}\)

=>\(\frac{-5}{6}x+\frac65+\frac{1}{10}=\frac{7}{15}\)

=>\(-\frac56x+\frac{13}{10}=\frac{7}{15}\)

=>\(-\frac56x=\frac{7}{15}-\frac{13}{10}=\frac{14}{30}-\frac{39}{30}=\frac{-25}{30}=-\frac56\)

=>x=1

a: =>5x+25-3x+6=25+18

=>2x+41=43

=>2x=2

=>x=1

b: =>4x+8=3x+3+17

=>4x+8=3x+20

=>x=12

a: =>5x+25-3x+6=25+18

=>2x+41=43

=>2x=2

=>x=1

b: =>4x+8=3x+3+17

=>4x+8=3x+20

=>x=12

3: Số học sinh giỏi là 40*1/5=8 bạn

Số học sinh trung bình là 32*3/8=12 bạn

Số học sinh khá là 32-12=20 bạn

1:

a: -1/3+7/6=7/6-2/6=5/6

b: 5/7-3/5=25/35-21/35=4/35

c: 0,75*4/5=4/5*3/4=3/5