Logarithmic Properties in Proving Equations

In summary, the conversation discusses proving the statement log((a+b)/7)=1/2(loga+logb) using multiple log properties. The conversation also touches on factoring and simplifying equations.
  • #1
Sorry!
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Homework Statement


Given a^2+b^2=47ab provehat log((a+b)/7)=1/2(loga+logb)


The Attempt at a Solution


I am assuming it is using multiple log properties... idk how though :|
 
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  • #2
What can be added to both sides such that a^2+b^2 can be become (a+b)2?
 
  • #3
ooooooh so is this right?

(a+b)^2=49ab
a+b=7(ab)^(1/2)
(a+b)/7=(ab)^1/2

log((a+b)/7)=1/2(loga+logb)
?
 
  • #4
(a+b)^2=49ab
a+b=7(ab)^(1/2)
(a+b)/7=(ab)^1/2

so log [ (a+b)/7 ] = log [ (ab)^(1/2)]

log (ab)^1/2 = 1/2 log ab = 1/2 (log a + log b)
 
  • #5
yeah i got it :D

man that was so easy. i feel so stupid took 0/6 on my test ha :|

thanks for the help astronuc
 
  • #6
Yeah - one just has to learn to think about factoring things and sometimes adding or subtracting from both sides of an equation to simplify it, or add, subtract and regroup on the same side.
 

FAQ: Logarithmic Properties in Proving Equations

How do I simplify logarithmic expressions using multiple log properties?

To simplify logarithmic expressions, you can use several log properties such as the product, quotient, and power properties. These properties allow you to rewrite logarithmic expressions in a simpler form by combining multiple logarithms or breaking down a single logarithm into smaller parts.

Can I use multiple log properties in any order?

Yes, you can use multiple log properties in any order as long as you follow the basic rules of logarithms. For example, you can use the product property first and then the quotient property, or vice versa, to simplify an expression. However, it is important to remember that the order of operations still applies, so you may need to use parentheses to indicate which operations should be performed first.

How do I know which log property to use in a given problem?

In order to determine which log property to use, you should first identify the type of expression you are dealing with. If the expression involves multiplication, division, or raising a logarithm to a power, then you can use the product, quotient, or power property, respectively. If the expression involves adding or subtracting logarithms, then you can use the sum or difference property. It may also be helpful to rewrite the expression in a different form to make it easier to apply the log properties.

Are there any common mistakes to avoid when using multiple log properties?

One common mistake to avoid is applying the wrong log property to an expression. This can happen if you are not familiar with the different log properties or if you rush through the problem without carefully considering which property to use. It is also important to remember to distribute any coefficients or exponents when using log properties, as this is a common source of errors.

Can I use multiple log properties to solve equations?

Yes, you can use multiple log properties to solve equations involving logarithms. However, it is important to be cautious when using log properties to solve equations, as it is possible to introduce extraneous solutions. It is always recommended to check your solutions by plugging them back into the original equation to ensure they are valid.

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