Let's say you're working with this one:


f(x) = ln(x-8)

, The natural log has to be a positive number, so set the terms inside the parentheses to greater than zero to make it so. Here's what you do:


x - 8 > 0

, Just isolate the variable x by adding 8 to both sides. Here's how:


x - 8 + 8 > 0 + 8
x > 8

, Show that the domain for this equation is equal to all numbers greater than 8 until infinity. Here's how:


D = (8,∞)
Write the problem.
Set the terms inside the parentheses to greater than zero.
Solve.
State the domain.
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