Finding a solution to the equation x3^(2x+1)=9x

  • Thread starter Mppl
  • Start date
In summary, the first step in solving this equation is to use logarithms to rewrite it in a simpler form. To solve for x, we can use the power rule for logarithms and then solve the resulting quadratic equation using the quadratic formula. This equation cannot be solved without using logarithms due to the power of x in the exponent. There are two special cases to consider when solving this equation, x=0 and x=1. This equation can have multiple solutions, including two distinct values for x or a repeated solution if the discriminant is equal to 0.
  • #1
Mppl
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how can I know that zero is the solution of x3^(2x+1)=9x

I mean I know that it is the solution cause if I substitute zero I'll get an equality but how can I find it?
 
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  • #2
Is this the equation you want to solve:
[tex]x3^{2x+1}=9x[/tex]?
If so, [tex]x3^{2x+1}=9x\Leftrightarrow x(3^{2x+1}-9)=0\Leftrightarrow x=0\text{ or } 3^{2x+1}=3^2\Leftrightarrow 2x+1=2\Leftrightarrow x=\frac{1}{2}[/tex]
 
  • #3
oh thanks man, all I could think about was to divide both sides by x. Thats so simple...

Thank you very much
 
  • #4
Just happy to help
 

1. What is the first step in solving this equation?

The first step in solving this equation is to rewrite it in a simpler form by using logarithms. We can take the log base 3 of both sides to get: (2x+1)log3(x3)=log3(9x).

2. How do I solve for x in this equation?

After rewriting the equation in a simpler form, we can use the power rule for logarithms to distribute the exponent (2x+1) to both terms inside the parenthesis. This will result in: (2x+1)(log3x+1)=log3(9x). We can then expand the left side and simplify the right side to get a quadratic equation in terms of x, which we can then solve using the quadratic formula.

3. Can this equation be solved without using logarithms?

No, this equation cannot be solved without using logarithms. The power of x in the exponent makes it difficult to solve without logarithmic functions.

4. Are there any special cases to consider when solving this equation?

Yes, there are two special cases to consider when solving this equation. If x=0, then the left side of the equation becomes 0 and the right side becomes undefined. If x=1, then the left side becomes 1 and the right side becomes 0.

5. Can this equation have more than one solution?

Yes, this equation can have multiple solutions. When solving the quadratic equation, we may get two distinct values for x, or we may get a repeated solution if the discriminant is equal to 0.

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