Which rule describes a nonlinear function?

a. x + y = 100

b. y = 8/x

c. 9 = 11x - y

d. x = y

Answer : y = 8/x

We know that linear function have constant slope.

In a linear function y=mx+b, the slope is m

Lets analyze each option

x + y = 100

y = - x + 100

Here slope is - 1. It is a linear function.

y=8/x

Here x is in the denominator and it is not in the form of y=mx+b

So it is non-linear function.

9 = 11x - y

y = 11x + 9

Here slope is 11. It is a linear function.

x = y

y=x that has slope 1. It is a linear function.