\(\dfrac{9^4.8^6}{6^{10}.16^3}=\dfrac{\left(3^2\right)^4.\left(2^3\right)^6}{3^{10}.2^{10}.\left(2^4\right)^3}=\dfrac{3^8.2^{18}}{3^{10}.2^{22}}=\dfrac{1}{9.4}=\dfrac{1}{36}\)

\(\left(\dfrac{4}{5}x-1\right).\left(6x+\dfrac{1}{2}\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}\dfrac{4}{5}x-1=0\\6x+\dfrac{1}{2}=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}\dfrac{4}{5}x=1\\6x=\dfrac{-1}{2}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{4}\\x=\dfrac{-1}{12}\end{matrix}\right.\)

vậy \(x\in\left\{\dfrac{-1}{12};\dfrac{5}{4}\right\}\)

\(\left(2x+1\right)^2=25\)

\(\left(2x+1\right)^2=\left(\pm5\right)^2\)

\(2x+1=\pm5\)

+)\(2x+1=5\Rightarrow2x=4\Rightarrow x=2\)

+)\(2x+1=-5\Rightarrow2x=-6\Rightarrow x=-3\)

vậy \(x\in\left\{-3;2\right\}\)

\(x:8,5=0,69:\left(-1,15\right)\)

\(\Rightarrow x:8,5=-0,6\)

\(\Rightarrow x=-0,6.8,5=-5,1=\dfrac{-51}{10}\)

vậy \(x=\dfrac{-51}{10}\)

\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{6}\) và \(x.y.z=720\)

đặt \(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{6}=k\)

\(\Rightarrow\left\{{}\begin{matrix}x=3k\\y=5k\\z=6k\end{matrix}\right.\)

\(\Rightarrow3k.5k.6k=720\)

\(\Rightarrow90\).k\(^3\) \(=720\)

\(\Rightarrow k^3=720:90=8=(\pm2)^3\)

\(\Rightarrow k=\pm2\)

nếu \(k=2\Rightarrow\left\{{}\begin{matrix}x=6\\y=10\\z=12\end{matrix}\right.\)

nếu \(k=-2\Rightarrow\left\{{}\begin{matrix}x=-6\\y=-10\\z=-12\end{matrix}\right.\)

vậy nếu \(x=6\Rightarrow y=10\Rightarrow z=12\)

nếu \(x=-6\Rightarrow y=-10\Rightarrow z=-12\)

\(\dfrac{4}{9}:\left(\dfrac{-1}{7}\right)+6\dfrac{5}{9}.\left(\dfrac{2}{3}\right)\)

\(=\dfrac{4}{9}.\left(-7\right)+\dfrac{59}{9}.\dfrac{2}{3}\)

\(=\dfrac{2}{9}.\left(-14\right)+\dfrac{2}{9}.\dfrac{59}{3}\)

\(=\dfrac{2}{9}.\left(-14+\dfrac{59}{3}\right)\)

\(=\dfrac{2}{9}.\dfrac{17}{3}\)

\(=\dfrac{34}{27}\)

\(\left(\dfrac{-1}{3}\right)^2.\dfrac{4}{11}+\dfrac{7}{11}.\left(\dfrac{-1}{3}\right)^2\)

\(=\dfrac{1}{9}.\dfrac{4}{11}+\dfrac{7}{11}.\dfrac{1}{9}\)

\(=\dfrac{1}{9}.\left(\dfrac{4}{11}+\dfrac{7}{11}\right)\)

\(=\dfrac{1}{9}.1=\dfrac{1}{9}\)

Chọn số liệu thích hợp để điền vào chỗ trống trong câu sau : Thực vật trên Trái Đất hiện có khoảng trên … loài

A. 30 000  

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