Q&A for How to Understand Logarithms

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Can you provide some exam style questions of logarithms?

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Here are some few practice problems : 1. log(3 + 2 log(1+x) ) =0 , Find x 2. If (2.5)^x = 0.025)^y, find x and y.

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How do I find an answer for 6=log(x/5)?

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You must expand the expression to 6=log(x)-log(5). This is an example of the quotient property of a logarithm log(a/b)=log(a)-log(b). You then do log(5), which is approximately 0.699, so 6=log(x)-0.699. Add 0.699 to both sides to get 6.699=log(x). Then rewrite it in exponential form as 10^6.699=x and do the rest.

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How do you get ln(y)?

Community Answer

The ln(y) function is similar to a log function. A log function uses a base of ten (log base ten of x is often written log(x)), unless otherwise specified. A function ln(x) is just a logarithm with a base of e, a number that is similar to pi in the fact that it is a mathematical constant. The letter e represents the number 2.71828. So, ln(y) is equivalent to log of y with a base of e, or log base e of y.

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Where do I place X in a logarithm?

Community Answer

X is a variable. In a logarithm, the value to be found is denoted by X. (It can be either the base or argument.)

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Question

Can I calculate logs of negative numbers?

Community Answer

You can find the solution of a negative log, however the number that you find will not be rational so for all intents and purposes you cannot.

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What is the purpose of logarithms?

Sage Vetter

Community Answer

Logarithms provide a tool to solve problems. Another way to think of this, logarithms rewrite problems to indicate exponential numbers without using any powers in the actual equation. Logarithms provides greater access to all the numbers in the equation. This is the basic purpose of a log.

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What is the value of x in the equation log (x+1)+log (x-1)=log 3?

Community Answer

Simplify the left side to a single log (x^2-1). Then take the antilog of both sides (x^2-1=3). Solve resultant polynomial equation (x=2 or x= -2). Check solutions against original equation for domain issues. For example, if x=-2, log (x-1) is undefined, so it is not the correct solution.

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What is the solution to 3 log4?

Donagan

Top Answerer

That means 3 times the log of 4. The log (base 10) of 4 is approximately 0.6. 3 times 0.6 is 1.8. 1.8 is the antilog of 64. This is just another way of saying 4³ = 64.

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Log base2 (3x+1) - log base2 (2x-7) = 3

I_l1ke_gam3s

Community Answer

Notice they have the same base, You can then make this into log base 2 of (3x + 1 / 2x - 7) = 3. Make 2 the base on both sides. 3x + 1 / 2x - 7 = 8. Multiply both sides by the denominator. 3x + 1 = 8(2x - 7). 3x + 1 = 16x - 56. Add 56 to both sides and subtract 3x on both sides. 57 = 19x. Divide both sides by 19, so that x = 3.

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