Question

tim x thuoc z biet:

a)2^x-1+2^x+1+2^x+2=104

b)3^x+2+3^x+1+3^x+3^x-1=120

Answer 1

a) \(2^{x-1}+2^{x+1}+2^{x+2}=104\)

=> \(2^{x-1}+2^x\cdot2+2^x\cdot2^2=104\)

=> \(2^x:2+2^x\cdot\left(2+2^2\right)=104\)

=> \(2^x\cdot\frac{1}{2}+2^x\cdot6=104\)

=> \(2^x\cdot\left(\frac{1}{2}+6\right)=104\Rightarrow2^x=104:\left(\frac{1}{2}+6\right)=104:\frac{13}{2}=16\)

=> \(x=4\)

Answer 2

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