\(\left(\frac{2}{3}\right)^{17}:\left(\frac{2}{3}\right)^{15}+\frac{4}{9}.\left(-\frac{1}{2}\right)^3\)

\(=\left(\frac{2}{3}\right)^{17-15}+\frac{4}{9}.\left(-\frac{1}{8}\right)\)

\(=\left(\frac{2}{3}\right)^2+\frac{4}{9}.\left(-\frac{1}{8}\right)\)

\(=\frac{4}{9}+\frac{4}{9}.\left(-\frac{1}{8}\right)\).

\(=\frac{4}{9}.1+\frac{4}{9}.\left(-\frac{1}{8}\right)\)

\(=\frac{4}{9}.\left(-\frac{1}{8}+1\right)\)

\(=\frac{4}{9}.\frac{7}{8}\)

\(=\frac{7}{18}\)

\(\left(\frac{2}{3}\right)^{17}:\left(\frac{2}{3}\right)^{15}+\frac{4}{9}.\left(-\frac{1}{2}\right)^3\)

\(=\left(\frac{2}{3}\right)^{17-15}+\frac{2^2}{9}.\frac{-1}{2^3}\)

\(=\left(\frac{2}{3}\right)^2+\frac{-1}{18}\)\(=\frac{4}{9}-\frac{1}{18}=\frac{7}{18}\)

\(\left(\frac{2}{3}\right)^{17}:\left(\frac{2}{3}\right)^{15}+\frac{4}{9}.\left(-\frac{1}{2}\right)^3\)

\(=\left(\frac{2}{3}\right)^{17-15}+\frac{2^2}{9}.\frac{-1}{2^3}\)

\(=\left(\frac{2}{3}\right)^2+\frac{-1}{18}\)

\(=\frac{4}{9}-\frac{1}{18}=\frac{7}{18}\)

Đặt \(\frac{a}{b}=\frac{c}{d}=t\Rightarrow\hept{\begin{cases}a=bt\\c=dt\end{cases}}\)

\(\frac{a^2-c^2}{b^2-d^2}=\frac{\left(bt\right)^2-\left(dt\right)^2}{b^2-d^2}=t^2\)

\(\frac{ac}{bd}=\frac{bt.dt}{bd}=t^2\)

Suy ra đpcm. 

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Khi nào rảnh vào kênh H-EDITOR xem vid nha!!! Thanks!

\(A=1,\left(35\right)-\frac{0,1\left(35\right)}{2,2}\)

\(\Rightarrow10A=13,\left(53\right)-\frac{1,\left(35\right)}{2,2}\)

\(\Rightarrow10A=13+0,\left(53\right)-\frac{1+0,\left(35\right)}{2,2}\)

\(\Rightarrow10A=13+\frac{53}{99}-\frac{1+\frac{53}{99}}{2,2}\)

\(\Rightarrow10A=\frac{1340}{99}-\frac{\frac{152}{99}}{2,2}\)

\(\Rightarrow10A=\frac{1340}{99}-\frac{152.2,2}{99}\)

\(\Rightarrow10A=\frac{1340}{99}-\frac{152.22:10}{99}\)

\(\Rightarrow10A=\frac{1340}{99}-\frac{152.2:10}{9}\)

\(\Rightarrow10A=\frac{1340-304}{9.10}\)

\(\Rightarrow10A=\frac{1036}{90}\)\(\Rightarrow A=\frac{1036}{900}=\frac{259}{225}\)

Vì ( 2x + 7 )2 ≥ 0 ∀ x

\(\Rightarrow E=\left(2x+7\right)^2+\frac{2}{5}\ge\frac{2}{5},\forall x\)

Dấu "=" xyar ra <=> 2x + 7 = 0

<=> 2x = -7

<=> x = -3,5

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em lấy 180^o - ( dữ liệu đã biết ) là ra