Question

What is the domain of the function f(x)=45/(x-23)?

Answer 1

Hello. x-23≠0 ; x-23=0 ; x= 23 ; S=]-∞;23[U]23;+∞[

Answer 2

domain is the set of numbers you can use
usually, domain=all real numbers except those that divide by zero

so find those exceptions
find what numbers make deonenator equal to 0 and exclude them
x-23 is denom
x-23=0
x=23

doman is all real numbers except 23