Solving Simultaneous Equations Using Logarithms

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In summary, simultaneous equations are a set of equations with multiple variables that are solved together to find values that satisfy all equations. Logarithms are used to solve them by transforming exponential equations into linear ones, making them easier to solve. To solve simultaneous equations using logarithms, identify the variable with an exponent in each equation, take the logarithm of both sides, and simplify to get a system of linear equations. Logarithms are commonly used for problems involving exponential growth, compound interest, and equations with variables in the exponents. However, they may not always be the most efficient method and have limitations in their applicability to all types of simultaneous equations.
  • #1
synkk
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Homework Statement


Solve the simultanious equations
[tex] 2log_2y = log_43 + log_2x [/tex]
[tex]3^y = 9^x [/tex]

The Attempt at a Solution


[tex] 3^y = (3^2)^x [/tex]
[tex] y = 2x [/tex]

[tex]2log_2 x + 2log_2 2 = log_2 \sqrt{3} + log_2 x[/tex]
[tex]log_2 x = log_2 \frac{\sqrt{3}}{4}[/tex]


No idea what to do from where, what does x equals?
 
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  • #2
Correct up to now.
The only steps that remain to be done is to use

2log(...) = log[(...)[itex]^{2}[/itex]] and

logu + logv = log (uv)
 
  • #3
If logax = logay, then x = y.
 
  • #4
Ah okay, thank you guys.
 

FAQ: Solving Simultaneous Equations Using Logarithms

1. What are simultaneous equations?

Simultaneous equations are a set of two or more equations that contain multiple variables and are solved together to find the values of those variables that satisfy all equations.

2. Why use logarithms to solve simultaneous equations?

Logarithms are used to solve simultaneous equations because they allow us to transform exponential equations into linear ones, which are easier to solve. This method is particularly useful when the equations involve variables in the exponents.

3. How do I solve simultaneous equations using logarithms?

To solve simultaneous equations using logarithms, first identify the variable with an exponent in each equation. Then, take the logarithm of both sides of each equation to eliminate the exponent. After simplifying, you will have a system of linear equations that can be solved using traditional methods.

4. What are the common types of problems that can be solved using logarithms?

Logarithms are commonly used to solve problems involving exponential growth or decay, compound interest, and geometric sequences. They are also useful for solving equations that involve variables in the exponents, such as exponential equations and logarithmic equations.

5. Are there any limitations to using logarithms to solve simultaneous equations?

While logarithms are a powerful tool for solving simultaneous equations, they may not always be the most efficient method. In some cases, substitution or elimination may be a faster and simpler approach. Additionally, logarithms can only be used to solve equations with variables in the exponents, so they may not be applicable to all types of simultaneous equations.

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