\(|7-2x|=x+5\)

=> \(\orbr{\begin{cases}7-2x=x+5\\7-2x=-x-5\end{cases}\Leftrightarrow\orbr{\begin{cases}3x=2\\x=12\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{2}{3}\\x=12\end{cases}}}\)

Mình tí giải tiếp cho bạn nhé,mình còn đang làm bài bồi toán(thông cảm)

1)11/24-5/41+13/24+0,5-36/41=(11/24+13/24)-(5/41+36/41)+0,5=24/24-41/41+0,5=1-1+0,5=0,5

2)15/34+7/21+19/34-1​​và 15/17+2/3=(15/34+19/34)+(1/3+2/3)-32/17=34/34+3/3-32/17=1+1/32/17=2+32/17=34/17+32/17=66/17

3)1 và 4/23+5/21-4/23+0,5+16/21=(27/23-4/23)+(5/21+16/21)+0,5=23/23+21/21+0,5=1+1+0,5=2,5

4)(-12):(3/4-5/6)²=(-12):(9/12+10/12)²=(-12):(19/12)²=(-12):19²/12²=(-19)²/12=361/12

\(x-25\%+x=0,5\)

\(\Rightarrow\left(x+x\right)-\frac{1}{4}=\frac{1}{2}\)

\(\Rightarrow2x=\frac{1}{2}+\frac{1}{4}\)

\(\Rightarrow2x=\frac{3}{4}\)

\(\Rightarrow x=\frac{3}{4}:2\)

\(\Rightarrow x=\frac{3}{8}\)

a) \(\left|x\right|+\left|x+2\right|=0\)

Mà \(\left|x\right|\ge0\forall x;\left|x+2\right|\ge0\forall x\)

\(\Rightarrow\left|x\right|+\left|x+2\right|\ge0\)

Dấu '' = '' xảy ra khi \(\Rightarrow\hept{\begin{cases}x=0\\x+2=0\end{cases}}\)\(\Rightarrow\hept{\begin{cases}x=0\\x=-2\end{cases}}\)

b) \(\left|x\right|=5,6\)

\(\Rightarrow x\in\left\{\pm5,6\right\}\)

Mà \(x< 0\Rightarrow x=-5,6\)

c) \(\left|x-3\right|+\left|4-x\right|=0\)

Mà: \(\hept{\begin{cases}\left|x-3\right|\ge0\forall x\\\left|x-4\right|\ge0\forall x\end{cases}}\)

Dấu '' = '' xảy ra khi \(\Rightarrow\hept{\begin{cases}x-3=0\\x-4=0\end{cases}}\)\(\Rightarrow\hept{\begin{cases}x=3\\x=4\end{cases}}\)

Mà x không thể nhận hai giá trị cùng một lúc \(\Rightarrow x\in\varnothing\)

d) 

\(\left|-x\right|=\frac{3}{4}\)

Mà \(\left|-x\right|=\left|x\right|\Rightarrow\left|x\right|=\frac{3}{4}\)

\(\Rightarrow x\in\left\{\pm\frac{3}{4}\right\}\)mà \(x< 0\Rightarrow x=\frac{-3}{4}\)

\(\left|a+b\right|=\left|a-b\right|\)

\(\Rightarrow\orbr{\begin{cases}a+b=a-b\\a+b=-\left(a-b\right)\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}a-a=-b-b\\a+b=-a+b\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}0=-2b\\a+a=b-b\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}b=0\\2a=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}b=0\\a=0\end{cases}}\)

\(|x|=\frac{1}{5}\)

=>  \(\orbr{\begin{cases}x=\frac{1}{5}\\x=-\frac{1}{5}\end{cases}}\)

\(x=\frac{1}{5}\)\(;-\frac{1}{5}\)

a) \(\sqrt{x-4}=64\left(ĐK:x\ge4\right)\)

\(\Rightarrow\left(\sqrt{x-4}\right)^2=64^2\)

\(\Rightarrow x-4=4096\)

\(\Rightarrow x=4100\)

b) \(x^2=64\)

\(\Rightarrow x^2=8^2\)

\(\Rightarrow x=8\)

a) \(3y\left(2y-4\right)-2y\left(3y+5\right)=44\)

\(\Rightarrow6y^2-12y-6y^2-10y=44\)

\(\Rightarrow\left(6y^2-6y^2\right)-\left(12y+10y\right)=44\)

\(\Rightarrow-22y=44\)

\(\Rightarrow y=-2\)

b) \(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)

\(\Rightarrow48x^2-12x-20x+5+3x-48x^2-7+112x=81\)

\(\Rightarrow83x-2=81\)

\(\Rightarrow x=1\)

a) 3^4-x = 3³

\(\Rightarrow\)4 - x = 3

              x = 4 - 3

              x = 1

b) ( x - \(\frac{4}{5}\))² = 0²

\(\Rightarrow\)x - \(\frac{4}{5}=0\)

         x         = 0 + \(\frac{4}{5}\)

         x         = \(\frac{4}{5}\)

a, đề bài

---> \(3^{4-x}=3^3\)

---> 4 - x = 3

---> x = 1

b, đề bài

---> \(x-\frac{4}{5}=0\)

---> \(x=\frac{4}{5}\)

xin tiick