Solving 10^(x+3)=5e^(7-x): Need Help!

  • Thread starter niteshadw
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In summary, the conversation is about a problem with a logarithm equation and the steps taken to solve it. The problem is simplified by rearranging the terms and using the natural logarithm function. The final solution is found by dividing the remaining terms. The person is grateful for the assistance provided.
  • #1
niteshadw
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I'm having a problem with a log question, its rather easy but I'm stuck after certain point.

The question is:

10^(x+3)=5e^(7-x)

I tried solving by:

ln10^(x+3) = ln5 + lne^(7-x)
(x+3)ln10 = ln5 + (7-x)

I am stuck after that, I've tried every combiantion and when I chack it with a calculator answer, my answer is different.

Any help would be much appreciated, thank you.
 
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  • #2
(x+3)ln10 = ln5 + 7-x that is correct. Now just put all of the x's to the left hand side and all the rest on the other side : xln10 + x = ln5 + 7 - 3ln10

x(ln10 + 1) = ln5 + 7 -3ln10

x = (ln5 + 7 - 3ln10)/(ln10 + 1)

marlon
 
  • #3
Ah, thank you very much. Your help is much appreciated. I could not fingure out how to get the x's out the correct way. I did not know this was allowed. Thank you again.
 

1. How do I solve this equation?

To solve this equation, you can use logarithms to isolate the variable x. First, take the natural logarithm of both sides to get ln(10^(x+3)) = ln(5e^(7-x)). Then, use the logarithm properties to simplify the equation to (x+3)ln(10) = ln(5) + (7-x). From here, you can solve for x by combining like terms and isolating the variable.

2. What do I do with the exponents?

The exponents in this equation can be simplified by using the properties of logarithms. Remember that the natural logarithm of a number raised to a power is equal to the power times the natural logarithm of the number. So, ln(10^(x+3)) = (x+3)ln(10). Use this property to simplify the equation before solving for x.

3. Can I use a calculator to solve this equation?

Yes, you can use a calculator to solve this equation. You will need to use the natural logarithm function and the exponential function (e^x) on your calculator. Make sure to double check your answer by plugging it back into the original equation.

4. Are there any other methods to solve this equation?

Yes, there are multiple methods to solve this equation. One method is to graph both sides of the equation and find the point of intersection. Another method is to use substitution, where you solve for one variable in terms of the other and then substitute it into the equation. However, using logarithms is typically the most efficient way to solve this type of equation.

5. What if I get a negative or complex answer?

If you get a negative or complex answer for x, it means that there is no real solution to this equation. This can happen when the equation has no real roots or when you make a mistake in your calculations. Double check your work and make sure you are using the correct properties of logarithms.

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