Question

3^x-1+5.3^x-1 =486

tìm x

ai nhanh mk tick

Answer 1

\(3^{x-1}+5.3^{x-1}=486\)

\(\Rightarrow3^{x-1}.\left(5+1\right)=486\)

\(3^{x-1}.6=486\)

\(3^{x-1}=81\)

\(3^{x-1}=3^4\)

\(\Rightarrow x-1=4\)

\(\Rightarrow x=5\)

Answer 2

<=> 3^x-1 +5.3^x-1 =486

<=> 3^x-1 . (1+5) = 486

<=> 3^x-1 . 6 =486

<=> 3^x-1 = 486 :6

<=> 3^x-1 = 81

<=> 3^x-1 = 3⁴

<=> X-1=4

<=> X = 4+1

<=> X=5

Answer 3

\(3^{x-1}+5.3^{x-1}=486\)

=> \(3^{x-1}.1+5.3^{x-1}=486\)

=> \(\left(3^{x-1}\right).1+5=486\)

=> \(\left(3^{x-1}\right).6=486\)

=> \(\left(3^{x-1}\right)=486:6\)

=> \(3^{x-1}=81\)

=> \(3^{x-1}=3^4\)

=> x - 1 = 4

           x = 4 - 1

           x = 3

Vậy x = 3

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