the complete question in the attached figure
we have that
f(x)=3x/(4x²-4)
we know that
the denominator can not be zero
so
(4x²-4)=0
4x²=4
x²=1----> x=(+/-)√1
x1=1
x2=-1
the values of x=1 and x= -1 make the denominator zero, therefore they do not belong to the domain of the function
the answer is
the domain of the function is all real numbers except 1 and -1