An even function #f# is defined such that #f(-x)=f(x)# for all #x# in the domain of #f#. Using this definition, we examine #f(-x)#: #f(-x)=(-x)^4-6^-4+3(-x)^2# #f(-x)=x^4-6^-4+3x^2# #f(-x)=f(x)#
Since #f(-x)=f(x)#, we have shown that the function #f# is indeed even.