Answer:
4x^4+5, 5x^2
Explanation:
There's a few ways to get non-linear functions
In these examples, they involve x being raised to something
So the only way they can be non-linear is through 5x^2 and 4x^4+5
Let's take a look at the other examples
y = x/4 can just be rewritten as y = 1/4x, so that's linear
y = x + 2^2 can be rewritten as y = x + 4, so that's linear
y = 3 - 5x can be rewritten as y = -5x + 3, so that's linear
4y = 3x can be rewritten as y = 3/4x, so that's linear
Best of luck