Solve 2^3x=7^(x+1): Logarithms Solution

  • Thread starter AbsoluteZer0
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    Logarithms
In summary, the conversation is about solving the equation 2^{3x} = 7^{x+1} and the suggested steps to solve it. The conversation also includes a question about the next step and a suggestion to move all terms involving x to one side and solve for x.
  • #1
AbsoluteZer0
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Homework Statement



[itex]2^{3x} = 7^{x+1}[/itex]

Homework Equations



N/A

The Attempt at a Solution



[itex]2^{3x} = 7^{x+1}[/itex]

I'm not entirely sure how to proceed from here. I'm assuming that the following is the right step towards the solution...

[itex](log2)(3x) = log(7)(x+1)[/itex]

...but I'm not entirely sure.

Any suggestions?

Thanks,
 
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  • #2
AbsoluteZer0 said:

Homework Statement



[itex]2^{3x} = 7^{x+1}[/itex]

Homework Equations



N/A

The Attempt at a Solution



[itex]2^{3x} = 7^{x+1}[/itex]

I'm not entirely sure how to proceed from here. I'm assuming that the following is the right step towards the solution...

[itex](log2)(3x) = log(7)(x+1)[/itex]

...but I'm not entirely sure.

Any suggestions?

Thanks,

You are doing just fine. Now solve for x.
 
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  • #3
I've arrived at

[itex]\frac{3x}{x+1} = \frac{log7}{log2}[/itex]

I'm not sure how to progress.
What should I do next?

Thanks,
 
  • #4
AbsoluteZer0 said:
I've arrived at

[itex]\frac{3x}{x+1} = \frac{log7}{log2}[/itex]

I'm not sure how to progress.
What should I do next?

Thanks,

You are kind of going the wrong way. You've got log(2)*3x=log(7)(x+1)=log(7)x+log(7). Move all the terms involving x to one side and solve for x. log(2) and log(7) are just numbers.
 
Last edited:

What is a logarithm?

A logarithm is the inverse function of exponentiation. It is used to solve exponential equations, such as 2^x = 8.

Why do we use logarithms to solve equations?

Logarithms allow us to solve equations where the variable is in the exponent. By taking the logarithm of both sides, we can bring the variable down as a coefficient and solve for it.

How do we solve 2^3x=7^(x+1) using logarithms?

To solve this equation, we first take the logarithm of both sides. We can use any base, but it is often easiest to use the natural logarithm (ln). This gives us ln(2^3x) = ln(7^(x+1)). Then, we can use the power rule of logarithms to bring the exponents down as coefficients, giving us 3x ln(2) = (x+1) ln(7). From here, we can solve for x using algebraic techniques.

Are there any restrictions when using logarithms to solve equations?

Yes, there are a few restrictions. First, the base of the logarithm must be positive and not equal to 1. Additionally, the argument (what is inside the parentheses) of the logarithm must be positive. Finally, when solving logarithmic equations, any potential solutions found must be checked to make sure they satisfy the restrictions.

Can we use any base when solving equations with logarithms?

Yes, we can use any base for logarithms when solving equations. However, it is often most convenient to use a base that cancels out the exponent on one side of the equation.

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