(90 - 30) : X - 3

60 : x = 3

x =60 : 3

x = ....

Học tốt

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a. |x|+|y|=1

+) |x|+|y|=0+1

=> x=0; y=+1

+) |x|+|y|=1+0

=> x=+1; y=0

b. |x|+|y|=0

Mà |x| > 0; |y| > 0

=> |x|+|y|=0+0

=> x=y=0.

a) x = 0; y = 1

b) x = y ; x,y thuộc Z

a) x = 1 hoặc -1  thì y = 0

x = 0 thì y = 1 hoặc -1

b)  x = y = 0

a) 2/3x +1/2 = 1/10

     => 2/3x = 1/10 - 1/2

          2/3x = -2/5

         => x = -2/5 : 2/3

             x = -3/5

b) (4,5 - 2x) : 3/4 = \(1\frac{1}{3}=\frac{4}{3}\)

=> 4,5 - 2x = 4/3 x 3/4

    4,5 - 2x = 1

        -2x = 4,5 - 1

        -2x = 3,5

        => x = 3,5 : (-2)

             x = - 1,75

c) x/4 = 5/20

    => x = 5/20 x 4

       x = 1

d) ?????

2/3x+1/2=1/10

<=>2/3x=1/10-1/2

<=>2/3x=-2/10

=>x=-2/10 chia 2/3=-3/10

ý kia tương tự

\(\frac{1}{8}+\frac{1}{24}+\frac{1}{48}+\frac{1}{80}+\frac{1}{120}\)

\(=\frac{1}{2}(\frac{1}{2.4}+\frac{1}{4.6}+\frac{1}{6.8}+\frac{1}{8.10}+\frac{1}{10.12})\)

\(=\frac{1}{2}(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+..+\frac{1}{10}-\frac{1}{12})\)

\(=\frac{1}{2}\cdot\left(\frac{1}{2}-\frac{1}{12}\right)=\frac{1}{2}\cdot\frac{5}{12}=\frac{5}{24}\)

\(1200:24-\left(19-x\right)=38\)

\(\Leftrightarrow50-\left(19-x\right)=38\)

\(\Leftrightarrow19-x=50-38\)

\(\Leftrightarrow19-x=12\)

\(\Leftrightarrow x=7\)

\(2-\left[\left(5\frac{5}{24}+x\right)-7\frac{5}{24}\right]=0\)

\(2-\left[\frac{125}{24}+x-\frac{173}{24}\right]=0\)

\(2-\left(\frac{-48}{24}+x\right)=0\)

\(\frac{-48}{24}+x=2-0=2\)

\(\Rightarrow x=4\)

P/s: Có thể tính sai :<

/x-2/ =0
=> x-2=0
=> x=0+2
=> x=2

như tìm x thường thôi mà

Vì | x - 2 | = 0 <=> x + 2 = 0 => x = - 2

Vậy x = - 2

\(x-\left\{x-\left[x-\left(x-1\right)\right]\right\}=1\)1

\(x-\left[x-\left(x-1\right)\right]=x-1\)

\(x-\left(x-1\right)=x-\left(x-1\right)=1\)

\(x-1=x-1\)

\(2x=0\Leftrightarrow x=0\)

A= |x+2|+5

có |x+2| > hoặc = 0

vậy |x+2| + 5 > hoặc = 5

nên GTNN A=5 <=> x+2=5

                                  x=5-2

                                  x=3 hoặc -7

nha

\(\frac{4}{3}.\left(\frac{1}{6}-\frac{1}{2}\right)\le x\le\frac{2}{3}.\left(\frac{-1}{6}+\frac{3}{4}\right)\)

\(\frac{4}{3}.\frac{-1}{3}\le x\le\frac{2}{3}.\frac{7}{12}\)

\(\frac{-4}{9}\le x\le\frac{7}{18}\)

\(\frac{-8}{18}\le x\le\frac{7}{18}\)

\(\Rightarrow\)X \(\in\) {\(\frac{-7}{18};\frac{-6}{18};\frac{-5}{18};\frac{-4}{18};\frac{-3}{18};\frac{-2}{18};\frac{-1}{18};0;\frac{1}{18};\frac{2}{18};\frac{3}{18};\frac{4}{18};\frac{5}{18};\frac{6}{18}\)}

Ta có:-(3-0,2.x)-80%=7,5

-3+0,2x-0,8=7,5

0,2x=7,5+3+0,8

X=11,3:0,2

X=56,5

Vậy x=56,5

Ta có:-(3-0,2.x)-80%=7,5

-3+0,2x-0,8=7,5

0,2x=7,5+3+0,8

X=11,3:0,2

X=56,5

Vậy x=56,5