How do you find the domain of #f(x)=(4+x)/(1-4x)#?
The denominator of f(x) cannot be zero as this would make f(x) undefined. Equating the denominator to zero and solving gives the value that x cannot be.
#"solve "1-4x=0rArrx=1/4larrcolor(red)" excluded value"#
#"domain is "x inRR,x!=1/4#