若3的X次方=12,3的Y次方=4,则27的X-Y次方等于?

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若3的X次方=12,3的Y次方=4,则27的X-Y次方等于?

若3的X次方=12,3的Y次方=4,则27的X-Y次方等于?
若3的X次方=12,3的Y次方=4,则27的X-Y次方等于?

若3的X次方=12,3的Y次方=4,则27的X-Y次方等于?
27^(x-y)
=(3^x)^3/(3^y)^3
=12^3/(4^3)
=3^3
=27

27^(x-y)=(3^3)^(x-y)=(3^(x-y))^3=(3^x/3^y)^3=(12/4)^3=3^3=27
(^代表次方)

3^x=12
3^y=4
3^x/3^y=12/4=3
3^(x-y)=4
27^(x-y)
=(3^3)^(x-y)
=3^3(x-y)
=[3^(x-y)]^3
=4^3
=64

3的X次方 除以 3的Y次方 得到X-Y=1
所以27的X-Y次方等于1!!!

因为3^x=12,3^y=4
所以3^(x-y)=(3^x)*[3^(-y)]=12*1/4=3
所以27^(x-y)=3^[3(x-y)]=3^[(x-y)3]=3^3=27

27^(x-y)
=(3^x)^3/(3^y)^3
=12^3/(4^3)
=3^3
=27

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