Solving Log Equations: 2^x * 4^(x+5) = 4^(2x-1)

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In summary, the conversation revolved around solving the equation 2^x multiplied by 4^(x + 5) = 4^(2x - 1), with one person providing a solution and the other person offering an alternative method involving a quadratic equation. The conversation ended with a reminder to add, not multiply, the indices in exponents.
  • #1
Corkery
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Homework Statement


Solve the equation:
2^x multiplied by 4^(x + 5) = 4^(2x - 1)


Homework Equations





The Attempt at a Solution



2^x multiplied by 2^2(x+5)=2^2(2x-1)
x(2x+10)=4x-2
2x^2+10x=4x-2

and that's as far as i could get before I was completely stuck. But this could be completely wrong.
 
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  • #2
When you have [tex]2^x2^{2x+10}[/tex], you don't multiply the indexes, you add them.
 
  • #3
As danago said, [tex]2^x2^{2x+10}= 2^{3x+10}= 2^{4x-2}[/tex]. That gives a simple linear equation for x.


However, IF 2x^2+10x=4x-2 had been correct, that shouldn't give you any problem. It is a quadratic equation and, if you can't factor it, you can use the quadratic formula!
 
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1. What is the first step in solving this log equation?

The first step in solving this log equation is to use the power rule for logarithms to expand the left side of the equation. This will give you two separate log terms.

2. How do you combine the two log terms on the left side of the equation?

To combine the two log terms, you can use the product rule for logarithms. This rule states that log(a*b) = log(a) + log(b). In this case, you will have log(2^x) + log(4^(x+5)).

3. How do you simplify the log terms on the left side of the equation?

You can use the properties of logarithms to simplify the log terms. In this case, you can use the power rule for logarithms to bring the exponents in front of the logs. This will give you x*log(2) + (x+5)*log(4).

4. How do you solve for x in this log equation?

Once the log terms are simplified, you can use algebraic methods to solve for x. In this case, you can use the distributive property to factor out x, leaving you with x*(log(2) + log(4)) + 5*log(4) = 4^(2x-1).

5. How many solutions does this log equation have?

This log equation could have one or two solutions. To determine the number of solutions, you will need to solve the equation and then check if your solutions are valid. If your solutions result in negative numbers or zero inside the logarithms, they are not valid solutions. If your solutions are valid, then there will be two solutions. If one of your solutions is not valid, then there will be one solution.

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