khong bằng bn =))

m tồi dữ v sao..

Có t ko =)))

là ai z hả:))

\(\left(x-5\right)\left(x-7\right)=0\\ \Rightarrow\left[{}\begin{matrix}x-5=0\\x-7=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=5\\x=7\end{matrix}\right.\)

Vậy \(x\in\left\{5;7\right\}\)

\(-\dfrac{4}{7}-x=\dfrac{3}{5}-2x\\ \Rightarrow-x+2x=\dfrac{3}{5}+\dfrac{4}{7}\\ \Rightarrow x=\dfrac{21}{35}+\dfrac{20}{35}\\ \Rightarrow x=\dfrac{41}{35}\)

Vậy `x=41/35`

__

\(\dfrac{3}{7}x-\dfrac{2}{3}x=\dfrac{10}{21}\\ \Rightarrow\left(\dfrac{3}{7}-\dfrac{2}{3}\right)x=\dfrac{10}{21}\\ \Rightarrow\left(\dfrac{9}{21}-\dfrac{14}{21}\right)x=\dfrac{10}{21}\\ \Rightarrow\dfrac{-5}{21}x=\dfrac{10}{21}\\ \Rightarrow x=\dfrac{10}{21}:\left(-\dfrac{5}{21}\right)\\ \Rightarrow x=-2\)

Vậy `x=-2`

\(\left(2x+2\right)^3=512\\ \Rightarrow\left(2x+2\right)^3=8^3\\ \Rightarrow2x+2=8\\ \Rightarrow2x=8-2\\ \Rightarrow2x=6\\ \Rightarrow x=\dfrac{6}{2}=3\)

\(\dfrac{x\left(1,5x+1\right)}{6}-\dfrac{\left(2-x\right)^2}{4}\ge\dfrac{5x}{2}-2\\ \Leftrightarrow\dfrac{2x\left(1,5x+1\right)}{12}-\dfrac{3\left(2-x\right)^2}{12}\ge\dfrac{6\cdot5x}{12}-\dfrac{2\cdot12}{12}\\ \Leftrightarrow\dfrac{3x^2+2x}{12}-\dfrac{3\left(4-4x+x^2\right)}{12}\ge\dfrac{30x}{12}-\dfrac{24}{12}\\ \Leftrightarrow\dfrac{3x^2+2x-12+12x-3x^2}{12}\ge\dfrac{30x-24}{12}\\ \Leftrightarrow14x-12\ge30x-24\\ \Leftrightarrow14x-30x\ge-24+12\\ \Leftrightarrow-16x\ge-12\\ \Leftrightarrow x\le\dfrac{12}{16}=\dfrac{3}{4}\)

\(\left(6^{2007}-6^{2006}\right):6^{2006}\\ =6^{2007}:6^{2006}-6^{2006}:6^{2006}\\ =6^{2007-2006}-6^{2006-2006}\\ =6^1-6^0\\ =6-1=5\)