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mn giúp mình làm bài này với ạ

Cihce · Accepted Answer

5. Tính:$a)\left[\left(\dfrac{2}{5}\right)^6.\left(\dfrac{2}{5}\right)^5\right]:\left(\dfrac{2}{5}\right)^9\=\left[\left(\dfrac{2}{5}\right)^{6+5}\right]:\left(\dfrac{2}{5}\right)^9\
=\left(\dfrac{2}{5}\right)^{11}:\left(\dfrac{2}{5}\right)^9\
=\left(\dfrac{2}{5}\right)^{11-9}\
=\left(\dfrac{2}{5}\right)^2\
=\dfrac{4}{25}$$b)\left[\left(\dfrac{3}{7}\right)^8:\left(\dfrac{3}{7}\right)^7\right].\left(\dfrac{3}{7}\right)\
=\left[\left(\dfrac{3}{7}\right)^{8-7}\right].\left(\dfrac{3}{7}\right)\
=\left(\dfrac{3}{7}\right)^1.\left(\dfrac{3}{7}\right)\
=\left(\dfrac{3}{7}\right)^{1+1}\
=\left(\dfrac{3}{7}\right)^2\
=\dfrac{9}{49}$$c)\left[\left(\dfrac{2}{5}\right)^9.\left(\dfrac{2}{5}\right)^4\right]:\left[\left(\dfrac{2}{5}\right)^7.\left(\dfrac{2}{5}\right)^3\right]\
=\left[\left(\dfrac{2}{5}\right)^{9+4}\right]:\left[\left(\dfrac{2}{5}\right)^{7+3}\right]\
=\left(\dfrac{2}{5}\right)^{13}:\left(\dfrac{2}{5}\right)^{10}\
=\left(\dfrac{2}{5}\right)^{13-10}\
=\left(\dfrac{2}{5}\right)^3\
=\dfrac{8}{125}.$Câu trả lời: 5. Tính:$a)\left[\left(\dfrac{2}{5}\right)^6.\left(\dfrac{2}{5}\right)^5\right]:\left(\dfrac{2}{5}\right)^9\=\left[\left(\dfrac{2}{5}\right)^{6+5}\right]:\left(\dfrac{2}{5}\right)^9\
=\left(\dfrac{2}{5}\right)^{11}:\left(\dfrac{2}{5}\right)^9\
=\left(\dfrac{2}{5}\right)^{11-9}\
=\left(\dfrac{2}{5}\right)^2\
=\dfrac{4}{25}$$b)\left[\left(\dfrac{3}{7}\right)^8:\left(\dfrac{3}{7}\right)^7\right].\left(\dfrac{3}{7}\right)\
=\left[\left(\dfrac{3}{7}\right)^{8-7}\right].\left(\dfrac{3}{7}\right)\
=\left(\dfrac{3}{7}\right)^1.\left(\dfrac{3}{7}\right)\
=\left(\dfrac{3}{7}\right)^{1+1}\
=\left(\dfrac{3}{7}\right)^2\
=\dfrac{9}{49}$$c)\left[\left(\dfrac{2}{5}\right)^9.\left(\dfrac{2}{5}\right)^4\right]:\left[\left(\dfrac{2}{5}\right)^7.\left(\dfrac{2}{5}\right)^3\right]\
=\left[\left(\dfrac{2}{5}\right)^{9+4}\right]:\left[\left(\dfrac{2}{5}\right)^{7+3}\right]\
=\left(\dfrac{2}{5}\right)^{13}:\left(\dfrac{2}{5}\right)^{10}\
=\left(\dfrac{2}{5}\right)^{13-10}\
=\left(\dfrac{2}{5}\right)^3\
=\dfrac{8}{125}.$

No Name · Answer

a, $\left[\left(\dfrac{2}{5}\right)^6.\left(\dfrac{2}{5}\right)^5\right]:\left(\dfrac{2}{5}\right)^9$

$=\left(\dfrac{2}{5}\right)^{6+5}:\left(\dfrac{2}{5}\right)^9=\left(\dfrac{2}{5}\right)^{11}:\left(\dfrac{2}{5}\right)^9=\left(\dfrac{2}{5}\right)^{11-9}=\left(\dfrac{2}{5}\right)^2=\dfrac{2^2}{5^2}=\dfrac{4}{25}$

b, $\left[\left(\dfrac{3}{7}\right)^8:\left(\dfrac{3}{7}\right)^7\right].\left(\dfrac{3}{7}\right)$

$=\left(\dfrac{3}{7}\right)^{8-7}.\dfrac{3}{7}=\dfrac{3}{7}.\dfrac{3}{7}=\dfrac{9}{49}$

Câu trả lời: a, $\left[\left(\dfrac{2}{5}\right)^6.\left(\dfrac{2}{5}\right)^5\right]:\left(\dfrac{2}{5}\right)^9$

$=\left(\dfrac{2}{5}\right)^{6+5}:\left(\dfrac{2}{5}\right)^9=\left(\dfrac{2}{5}\right)^{11}:\left(\dfrac{2}{5}\right)^9=\left(\dfrac{2}{5}\right)^{11-9}=\left(\dfrac{2}{5}\right)^2=\dfrac{2^2}{5^2}=\dfrac{4}{25}$

b, $\left[\left(\dfrac{3}{7}\right)^8:\left(\dfrac{3}{7}\right)^7\right].\left(\dfrac{3}{7}\right)$

$=\left(\dfrac{3}{7}\right)^{8-7}.\dfrac{3}{7}=\dfrac{3}{7}.\dfrac{3}{7}=\dfrac{9}{49}$

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