Math  /  Algebra

Question12. Why must the base of a logarithm be positive? [3 marks]

Studdy Solution

STEP 1

1. Logarithms are mathematical functions that are the inverse of exponentiation.
2. The base of a logarithm is a positive real number, not equal to 1.

STEP 2

1. Explain the definition and properties of logarithms.
2. Discuss the implications of having a non-positive base.
3. Conclude why the base must be positive.

STEP 3

A logarithm logb(a) \log_b(a) is defined as the exponent x x such that bx=a b^x = a .
The base b b must be a positive real number because exponentiation with a positive base is well-defined and results in real numbers for all real exponents.

STEP 4

If the base b b were zero or negative, the function bx b^x would not be well-defined for all real x x .
For example, a zero base would make bx=0 b^x = 0 for any positive x x , and undefined for zero or negative x x .
A negative base would result in complex numbers for non-integer exponents, which is not suitable for the real-valued logarithm function.

STEP 5

The base of a logarithm must be positive to ensure that the logarithmic function is well-defined and results in real numbers for all positive a a .
This ensures the function is continuous and behaves predictably across its domain.
The base of a logarithm must be positive to maintain the integrity and definition of the logarithmic function in real numbers.

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