Solving Equations with Exponents: How to Find the Value of x

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Discussion Overview

The discussion revolves around solving an equation involving exponents, specifically the expression \([a^{(3x+1)}][b^{(2x-2)}]\). Participants explore how to find the value of \(x\) under different conditions, including whether the expression can equal zero or a positive constant.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Tim initially asks how to solve the equation \([a^{(3x+1)}][b^{(2x-2)}]\) for \(x\), but does not provide a complete equation.
  • Some participants note that an equation should include an '=' sign, suggesting that the expression must equal a constant.
  • It is proposed that the equation could equal either 0 or a positive constant \(c\), with the latter being more feasible under certain assumptions.
  • One participant argues that if \(a\) and \(b\) are positive real numbers, the expression cannot equal 0, as the power of a positive number is never 0.
  • A suggestion is made to take the logarithm of both sides when equating to a positive constant \(c\), leading to a logarithmic form of the equation.
  • Tim expresses uncertainty about solving the logarithmic equation, particularly when dealing with different terms in the brackets.
  • Another participant provides a rearrangement of the logarithmic equation, aiming to offer a hint for further progress.

Areas of Agreement / Disagreement

Participants generally agree that the expression cannot equal zero if \(a\) and \(b\) are positive real numbers. However, there is no consensus on the best method to solve the equation or how to handle the different terms involved.

Contextual Notes

Participants have not fully resolved the mathematical steps necessary to isolate \(x\) in the context of the logarithmic equation. The discussion includes assumptions about the positivity of constants \(a\) and \(b\) that may affect the validity of proposed solutions.

tmt1
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Hi,

Is there a way to solve such an equation for x?

[a^(3x+1)][b^(2x-2)]Thanks,

Tim
 
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tmt said:
Hi,

Is there a way to solve such an equation for x?

[a^(3x+1)][b^(2x-2)]Thanks,

Tim

Hi Tim!

What's the equation?
An equation is supposed to have a '=' sign in it...
 
Re: SImple question

In this case, it could be any constant, either 0 or c, it is just because I am curious.

[a^(3x+1)][b^(2x-2)]=0

[a^(3x+1)][b^(2x-2)]=c
 
Re: SImple question

tmt said:
In this case, it could be any constant, either 0 or c, it is just because I am curious.

[a^(3x+1)][b^(2x-2)]=0

[a^(3x+1)][b^(2x-2)]=c

If we assume that $a$ and $b$ are positive real numbers, then it is not possible with 0.
That is because the power of a positive number is never 0.

With a positive constant $c$, I suggest you take the logarithm of both sides.
\begin{array}{}
a^{3x+1}b^{2x-2}&=& c \\
\ln \left( a^{3x+1}b^{2x-2}\right)&=&\ln c \\
(3x+1)\ln a + (2x-2)\ln b&=&\ln c
\end{array}
Perhaps you know how to solve that.
 
Re: SImple question

I like Serena said:
If we assume that $a$ and $b$ are positive real numbers, then it is not possible with 0.
That is because the power of a positive number is never 0.

With a positive constant $c$, I suggest you take the logarithm of both sides.
\begin{array}{}
a^{3x+1}b^{2x-2}&=& c \\
\ln \left( a^{3x+1}b^{2x-2}\right)&=&\ln c \\
(3x+1)\ln a + (2x-2)\ln b&=&\ln c
\end{array}
Perhaps you know how to solve that.

Okay, thanks that is helpful but I do not know how to solve it.

I could solve

(3x+1)ln a + (3x+1) ln b = lnc

x=[ln c / (ln a + ln b) -1 ] / 3

However since there are 2 different number in the brackets I don't know what to do.

Thanks,

Tim
 
$$(3x+1)\ln a + (2x-2)\ln b=\ln c $$

$$3x\ln a +\ln a+2x\ln b-2\ln b=\ln c$$

$$3x\ln a+2x\ln b=\ln c - \ln a+2\ln b$$

I think this should be a good hint but if not, see below. :)

$$x(3\ln a +2\ln b) = \ln c - \ln a+2\ln b $$
 

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