Is log8 (x/2) same as log8 x/2?

In summary, the conversation discusses the ambiguity of notation in the log function and emphasizes the importance of using parentheses to make expressions clear. The participants also suggest setting the variable equal to 1 to check properties in math.
  • #1
wzwz
1
0
Is log8 (x/2) same with log8 x/2?
 
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  • #2
wzwz said:
Is log8 (x/2) same with log8 x/2?
Can you compute them and find out?
 
  • #3
Depends on what is hidden behind this sloppy notation:
$$
\log (8 \cdot \dfrac{x}{2})\; , \; \log \dfrac{8x}{2} \; , \; \dfrac{x}{2} \cdot \log 8 \; , \; \log_8 \dfrac{x}{2} \; , \; \dfrac{1}{2}\cdot \log_8 x \; , \;\dfrac{1}{2}\cdot \log (8x) \; , \;\dfrac{1}{2}\cdot x \cdot \log 8
$$
Make your choice.
 
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  • #4
The order of operations is well defined for exponents, and multiplication, and addition, but how it works with the log function doesn't seem to be nearly so conventional. When in doubt, use parentheses. When I was a high school student studying algebra in 1972, I asked the teacher the same question, about the order of operations for the log function. He didn't know the answer, and/or didn't understand the question.
 
  • #5
wzwz said:
Is log8 (x/2) same with log8 x/2?
To elaborate on what @fresh_42 said, what you wrote isn't clear. The second expression might be interpreted as ##\frac{\log_8 x}{2}##, which is different from ##\log_8 \frac x 2##.
 
  • #6
Without parenthesis, I would read log8 x/2 as (log8 x)/2. Parenthesis are cheap. Use them.
 
  • #7
wzwz said:
Is log8 (x/2) same with log8 x/2?

First of all, use parentheses, everywhere. Even when they are redundant. Make it absolutely clear that no errors can be made if you follow the parentheses. Usually it doesn't matter much, but in this question, it is impossible to distinguish the bases from the actual values without proper parentheses and terms.

Instead of the forum helping you, just set x equal to anything and do what you think it is.

If you ever have to check a property in math, just set the variable equal to 1, and solve. It can be in logarithms, exponents, etc. Just make everything into simple numbers that can be calculated and check.
 

1. Is the base of the logarithm important in determining equality?

Yes, the base of the logarithm is crucial in determining equality. Changing the base of a logarithm can result in different numerical values, so it is important to pay attention to the base when solving equations.

2. Can logarithms with different bases be equivalent?

Yes, logarithms with different bases can be equivalent. This is known as the change of base formula, where logb x = loga x / loga b.

3. How can I simplify log8 (x/2)?

Log8 (x/2) can be simplified by using the quotient rule of logarithms, which states that logb (x/y) = logb x - logb y. In this case, log8 (x/2) would become log8 x - log8 2.

4. Is log8 (x/2) the same as log8 (x-2)?

No, log8 (x/2) is not the same as log8 (x-2). The former is a logarithmic expression while the latter is a numerical value, and they cannot be equated.

5. Can I solve equations involving logarithms without using a calculator?

Yes, equations involving logarithms can be solved without using a calculator by using properties and rules of logarithms, such as the power rule, product rule, and quotient rule.

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