-x-2/3=-6/7

=> -x= -6/7+2/3

=>-x= -4/21

=>x= 4/21

sai rồi bạn ơi

2+2+2+2+2+2+2+2+2+2=20 nha bạn

c)\(4x^4-101x^2+25=0\)

\(\Leftrightarrow4x^4-100x^2-x^2+25=0\)

\(\Leftrightarrow4x^2\left(x^2-25\right)-\left(x^2-25\right)=0\)

\(\Leftrightarrow\left(4x^2-1\right)\left(x^2-25\right)=0\)

\(\Leftrightarrow\left(2x-1\right)\left(2x+1\right)\left(x-5\right)\left(x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\2x+1=0\\x-5=0\\x+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{2}\\x=\frac{-1}{2}\\x=5\\x=-5\end{matrix}\right.\)

Vậy \(x\in\left\{\frac{1}{2};\frac{-1}{2};5;-5\right\}\)

tớ nghĩ không trùng nhau vào lúc nào cả 

a)\(\left(2x-1\right)^2=x+5\)

\(\Leftrightarrow4x^2-4x+1=x+5\)

\(\Leftrightarrow4x^2-5x-4=0\)

\(\Leftrightarrow4\left(x^2-\frac{5}{4}x-1\right)=0\)

\(\Leftrightarrow4\left(x^2-\frac{5}{4}x+\frac{25}{64}-\frac{89}{64}\right)=0\)

\(\Leftrightarrow4\left[\left(x-\frac{5}{8}\right)^2-\frac{89}{64}\right]=0\)

\(\Leftrightarrow4\left(x-\frac{5}{8}+\frac{\sqrt{89}}{8}\right)\left(x-\frac{5}{8}-\frac{\sqrt{89}}{8}\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-\frac{5}{8}+\frac{\sqrt{89}}{8}=0\\x-\frac{5}{8}-\frac{\sqrt{89}}{8}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{5-\sqrt{89}}{8}\\x=\frac{5+\sqrt{89}}{8}\end{matrix}\right.\)

Vậy \(x\in\left\{\frac{5-\sqrt{89}}{8};\frac{5+\sqrt{89}}{8}\right\}\)

1000 + 1000 + 1000 + 1000

= 1000 x 4

= 4000

=3378912

k nha

7x8=56

Ta có: \(\frac{x-2}{33}=\frac{-132}{2-x}\) 

Áp dụng tính chất : tích trung tỷ bằng tích ngoại tỷ

=> (x - 2).(2 - x) = 33.(-132)

=> (2x - 4) - (x² - 2x) = -4356

=> 4 - x² = - 4356

=> x² = 4 + 4356

=> x² = ?////