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Sub 505 (Easy)|   Algebra|   Exponents|      
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Bunuel
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If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x? 16 Aug 2017, 00:30
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E
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5% (low)

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81% (00:43) correct 19% (01:10) wrong based on 270 sessions

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If \(3^{-x}+3^{-x}+3^{-x}=1\), what is the value of x?

A. -1

B. -1/2

C. 1/3

D. 1/2

E. 1
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E
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Jagdishvenkat
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If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x? 16 Aug 2017, 00:39
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3(3^-x)=3^(1-x)=1
Implies x=1

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If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x? 16 Aug 2017, 01:49
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3/3^x=1; 3^1-x=3^0; 1-x=0; 1=x
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If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x? 16 Aug 2017, 07:16
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Bunuel
If \(3^{-x}+3^{-x}+3^{-x}=1\), what is the value of x?

A. -1

B. -1/2

C. 1/3

D. 1/2

E. 1
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\(3^{-x}+3^{-x}+3^{-x}=1\)

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

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

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

\(3^0 = 1\), Therefore substituting \(3^0\) in equation (i) we get;

\(3^{(-x+1)} = 3^0\)

\(-x+1 = 0\)

\(x = 1\)

Answer (E)...
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If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x? 16 Aug 2017, 07:24
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Bunuel
If \(3^{-x}+3^{-x}+3^{-x}=1\), what is the value of x?

A. -1

B. -1/2

C. 1/3

D. 1/2

E. 1
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3\(^{-x}\) = \(\frac{1}{3^{x}}\)

\(\frac{1}{3^{x}}\) + \(\frac{1}{3^{x}}\) + \(\frac{1}{3^{x}}\) = 1

\(\frac{1}{3}\) + \(\frac{1}{3}\) + \(\frac{1}{3}\) = 1

x = 1

Answer E
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If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x? 22 Aug 2017, 08:27
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X should be 1.
Inverse 3^-x and equate LHS & RHS using base and exponent concepts.
Option E.
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If 3^(-x)+3^(-x)+3^(-x)=1, what is the value of x? 22 Aug 2017, 10:49
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If 3−x+3−x+3−x=13−x+3−x+3−x=1, what is the value of x?

A. -1

B. -1/2

C. 1/3

D. 1/2

E. 1

=3/3^x=1
for this to be true only value of x can be 1, thus E is the correct answer.
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