Logarithms will help you here ..

Algebra Level 1

If a x = b a^x = b , b y = c b^y = c , c z = a c^z = a and a , b , c , > 0 a, b, c, > 0 and is not 1, then the value of x y z xyz is


The answer is 1.

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5 solutions

Darryl Yeo
Apr 14, 2014

Substitute c c in c z = a c^{z} = a for b b , then substitute b b for a x a^{x} . We get a x y z = a a^{xyz} = a , and from this we can get x y z = l o g a a xyz = log_{a}a , which is just 1 \boxed{1} .

That's true, but note that if a=0, then log0(d) is undefined for all d.

K. J. W. - 6 years, 11 months ago
Roger Erisman
Apr 23, 2015

Take ln of both sides of each equation, and bring exponents to front.

x ln a = ln b , y ln b = ln c , z ln c = ln a.

So, xyz = ln b/ ln a * ln c / ln b * ln a / ln c = 1 by cancellation.

K. J. W.
Jul 18, 2014

This problem is wrong. Take a=0,b=0 and c=0.

Then x,y and z can be any number besides 0.

Also, take a=-1,b=-1 and c=-1.

Then x,y and z can be any odd integers.

Manish Bhargao
Apr 14, 2014

such a simple problem...

wow what a solution

Rishabh Jain - 7 years ago
Mehmet Yaman
Apr 13, 2014

c^z=a ---->(c^z)^x=a^x- since a^x=b

so c^(x z)=b--------<[c^(z x)]^y=b^y=c

thus c^(x y z)=c

therefore x y z=1

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