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Mathematics 9 Online
OpenStudy (anonymous):

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OpenStudy (anonymous):

\[\huge \frac{ logx }{ b-c } = \frac{ logy }{ c-a } = \frac{ logz }{ a-b }\] Show That \[\huge x ^{a}y ^{b}z ^{c}=1\]

OpenStudy (anonymous):

I proved xyz=1

OpenStudy (akashdeepdeb):

From the equality given, we can get 3 equations. Take 2 equations at once. These are the equations when we cross multiply; we get: c.log x - a.log x = b.log y - c.log y From this equation we can get: log (x^c / x^a) = log (y^b / y^c) x^(c-a) = y^(b-c) Or x^(c-a)/y^(b-c) = 1 You should do the same with the other equations too: a.log y- b.log y = c.log z - a.log z a.log x - b.log x = b.log z - c.log z And then you'd have to multiply all the equations. And I THINK it should give you the answer. Just try it once. Did you get what I did there? ^ :)

OpenStudy (anonymous):

log (y^a /y^b) = log ( z^c/ z^a) y^(a-b)/z^(c-a) = 1

OpenStudy (akashdeepdeb):

Yes! Excellent! Now you've got to do the same with the third equation. A then multiply the new equations. But did you understand how the given equations are turning to the equations at need? That is more important.

OpenStudy (anonymous):

Yeah i know the log properties but i didn't get that intuition BTW are you in CBSE board or SSE It seems you are in 12 th

OpenStudy (akashdeepdeb):

Yes. I am in 12th in a CBSE board.

OpenStudy (anonymous):

a.log x - b.log x = b.log z - c.log z logx^a - logx^b = logz^b - logz^c x^(a-b) = z^(b-c)

OpenStudy (akashdeepdeb):

Yes, now divide till you get the RHS as 1. And then, multiply all the equations you get. Hopefully, you wouldn't get 1=1. :P

OpenStudy (akashdeepdeb):

You wouldn't! NOTE: As it turns out, there are 3 equations with all the variables. And thus, one a,b,c is bound to be left out. :D

OpenStudy (anonymous):

\[\huge \frac{ x ^{a-b} }{ z ^{b-c} }=\frac{ y ^{a-b} }{ z ^{c-a} }=\frac{ x ^{c-a} }{ y ^{b-c} }\]

OpenStudy (anonymous):

After that

OpenStudy (akashdeepdeb):

No quite like that. I was telling you take the other individual equations [The ones which have a '1' on the RHS] And then multiply all of them because, then the RHS will finally have '1'.

OpenStudy (anonymous):

I am not getting you sorry

OpenStudy (anonymous):

Which equations you are talking about

OpenStudy (akashdeepdeb):

Here. Like I showed you, I had got \[\frac{x^{c-a}}{y^{b-c}} = 1\] Then you found this: \[\frac{y^{a-b}}{z^{c-a}} = 1\] And then again from the 3rd equation, you got this: \[\frac{x^{a-b}}{z^{b-c}} = 1\] Now just multiply these 3 equations, and you'd have your required answer. But you should check @ranga 's solution too, as he may have a shorter one. :)

OpenStudy (ranga):

\[\Large \frac{ logx }{ b-c } = \frac{ logy }{ c-a } = \frac{ logz }{ a-b } = k\] log(x) = k(b-c); alog(x) = ka(b-c) log(y) = k(c-a); blog(y) = kb(c-a) log(z) = k(a-b); clog(z) = kc(a-b) alog(x) + blog(y) + clog(z) = k(ab - ac + bc - ba + ca - cb) = 0 log(x^a * y^b * z^c) = log(1) x^a * y^b * z^c = 1

OpenStudy (akashdeepdeb):

Arrghh! I always forget to use the constant to do these. -__- Use that! ^

OpenStudy (anonymous):

Interesting! Thank you all of you

OpenStudy (akashdeepdeb):

You'd get the answer, either ways. :)

OpenStudy (ranga):

You are welcome.

OpenStudy (anonymous):

@AkashdeepDeb Did u give IIT jee (mains) this year?

OpenStudy (akashdeepdeb):

I did study for it. But no. I'd give it next year. I just started 12th. :P

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