a function is even if it can be reflected across the y axis and map onto itself
basically f(x) is even if f(-x)=f(x)
easy way to test is to see if f(-x)=f(x)
[tex](-x)^4-(-x)^3=x^4-x^3[/tex]
[tex]x^4-(-x^3)=x^4-x^3[/tex]
[tex]x^4+x^3=x^4-x^3[/tex]
nope, not even
answer is A