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Expanding logarithms calculator

Expand the logarithm of a product, quotient or power and check its numerical value. Enter positive arguments and a common logarithm base.

Calculator

Result
1.0000000000
First log term
0.3010299957
Second log term
0.6989700043
Expanded expression
log_10(2) + log_10(5)

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How this calculator works

Choose the structure inside the logarithm. Products split into addition, quotients split into subtraction, and powers become coefficients. The individual log terms are shown before they are combined. Arguments must be positive so each expanded term remains a real number. There is no corresponding rule that splits the logarithm of a sum.

Formula

log_n(ab) = log_n(a) + log_n(b); log_n(a/b) = log_n(a) - log_n(b); log_n(a^k) = k log_n(a).

Worked example

log_2(2 times 4) expands to 1 + 2 = 3. log_2(2^3) expands to 3 times 1 = 3.

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Frequently asked questions

Can I expand log(a + b)?

No. The product rule applies to multiplication inside the logarithm, not addition.

Why is log((-2)(-3)) rejected?

The product is positive, but the expanded real logarithms of -2 and -3 do not exist.

Does the power need to be an integer?

No. With a positive argument, a finite real exponent can move outside the logarithm.

Sources

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