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\(|x-7|+13=25\)

\(|x-7|=12\)

\(\Rightarrow\orbr{\begin{cases}x-7=12\\x-7=-12\end{cases}\Leftrightarrow\orbr{\begin{cases}x=19\\x=-5\end{cases}}}\)

\(|x-3|-16=-4\\ \Rightarrow|x-3|=14\)

\(\Rightarrow\orbr{\begin{cases}x-3=14\\x-3=-14\end{cases}\Leftrightarrow\orbr{\begin{cases}x=17\\x=-11\end{cases}}}\)

\(26-Ix+9I=-13\)

\(\Rightarrow|x+9|=39\)

\(\Rightarrow\orbr{\begin{cases}x+9=39\\x+9=-39\end{cases}\Leftrightarrow\orbr{\begin{cases}x=30\\x=-48\end{cases}}}\)

\(|x-5|=3\)

\(\Rightarrow\orbr{\begin{cases}x-5=3\\x-5=-3\end{cases}\Leftrightarrow\orbr{\begin{cases}x=8\\x=2\end{cases}}}\)

\(|1-x|=7\)

\(\Rightarrow\orbr{\begin{cases}1-x=7\\1-x=-7\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-6\\x=8\end{cases}}}\)

\(|2x+5|=1\)

\(\Rightarrow\orbr{\begin{cases}2x+5=1\\2x+5=-1\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=-3\end{cases}}}\)

\(\text{11 _ 12 +13 _ 14 + 15 - 16 + 17 _ 18 + 19 _20}\)

\(=\left(11-12\right)+\left(13-14\right)+\left(15-16\right)+\left(17-18\right)+\left(19-20\right)\)

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

\(=-5\)

\(\text{101 _ 102 _ ( - 103 ) _ 104 _ ( - 105 ) _ 106 _ ( -107 ) _ 108 _ ( - 109 ) _ 110}\)

\(=\left(101-102\right)+\left(-\left(-103\right)-104\right)+\left(-\left(-105\right)-106\right)\)\(+\left(-\left(-107\right)-108\right)+\left(-\left(-109\right)-110\right)\)

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

\(=-5\)

\(\text{1 + ( - 3 ) +5 + ( -7 ) + ... + ( - 1999 ) + 2001}\)

\(=\left(1+\left(-3\right)\right)+\left(5+\left(-7\right)\right)+...+\left(\left(-1999\right)+2001\right)\)

\(=-2+\left(-2\right)+...+\left(-2\right)\)Có 500 thừa số (-2)

\(=\left(-2\right).500\)

\(=-1000\)

\(\text{1 + ( -2 ) + 3 + ( -4) + ... + 2001 + ( - 2002)}\)

\(=\left(1+\left(-2\right)\right)+\left(3+\left(-4\right)\right)+...+\left(2001+\left(-2002\right)\right)\)

\(=-1+\left(-1\right)+...+\left(-1\right)\)Có 1000 thừa số (-1)

\(=\left(-1\right).1000\)

\(=-1000\)

chúc bạn học tốt

Có 2 trường hợp : 

+++  x-1 = 2x-5   => x-2x = -5+1 =>>>>>>> -x = -4 =>>>>>>>>>>>>>>>> X=4

+++  x-1 = -2x+5 => x+2x = 5+1 =>>>>> 3x=6 =>>>>>>>>>>>>>>>>>>>X=2

`@` `\text {Ans}`

`\downarrow`

`a,`

\(x \div 0,1 + x \div 0,25 - 35 = 35\)

`\Rightarrow x * 10 + x * 4 - 35 = 35`

`\Rightarrow x*(10+4) - 35 = 35`

`\Rightarrow 14x - 35 = 35`

`\Rightarrow 14x = 70`

`\Rightarrow x=70/14 =5`

Vậy, `x=5`

`b,`

\(x \div 0,125 - x \div 0,5 = 108\)

`\Rightarrow x * 4/5 - x*2=108`

`\Rightarrow x*(4/5 - 2) = 108`

`\Rightarrow -6/5x = 108`

`\Rightarrow x=108 \div -6/5`

`\Rightarrow x=-90`

Vậy, `x=-90.`

a) x/0,1 + x/0,25 - 35 = 35

x . 10 + x . 4 = 35 + 35

14x = 70

x = 70 : 14

x = 5

cảm ơn nhé

b) Ta có: 2(x-2)<5x+2

\(\Leftrightarrow2x-4-5x-2< 0\)

\(\Leftrightarrow-3x< 6\)

hay x>-2

Tìm x

\(\frac{x}{24}=-\frac{11}{40}+\frac{2}{5}\)

\(\frac{x}{24}=\frac{1}{8}\)

\(=>\frac{3}{24}=\frac{1}{8}\)

\(=>x=3\)

Vậy \(x=3\)

\(\frac{x}{24}=\frac{-11}{40}+\frac{2}{5}\)

=>\(\frac{x}{24}=\frac{1}{8}\)

=>x=3

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