(\frac{2}{5})^x -(\frac{5}{2}^x\frac{5}{2}-\frac{3}{2}=0<=>2(\frac{2}{5})^2x -3(\frac{2}{5})^x -5=0<=>((\frac{2}{5})^x +1)((\frac{2}{5})^x -3)=0
$(\frac{2}{5})^x -(\frac{5}{2}^x\frac{5}{2}-\frac{3}{2}=0
$$<=>2(\frac{2}{5})^2x -3(\frac{2}{5})^x -5=0
$$<=>((\frac{2}{5})^x +1)((\frac{2}{5})^x -3)=0
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