Here in this question, we want to know if either of the function is even , odd or neither
For an even function, the additive inverse of the value of the independent variable will give the same value of the dependent variable. An odd function will behave otherwise.
What this mean in plain terms is that for an even function;
f(x) = F(-x)
f(x) = 4x^2 + x^4
Let us find f(1)
f(1) = 4(1)^2 + 1^4 = 4 + 1 = 5
f(-1) = 4(-1)^2 + (-1)^4
f(-1) = 4 + 1 = 5
In this case, since f(1) = f(-1), then the function is even.
