Which function is nonlinear?

A.) 9Y + 3 = 0

B.) Y - 4X = 1

C.) Y = 2 + 6X^4

D.) X - 2Y = 7

E.) X^Y + 1 = 2

Any function which is of the form

y=mx+b, or Ax+By = C, is known as Linear function.

Now the function which are not of these two forms will be non linear function.

Or in other words we can say that the function with some exponent (positive or negative) on the variables, are non linear function.

And in the given options

C and E are Non Linear Functions

C.) Y = 2 + 6X^4

E.) X^Y + 1 = 2