**Consider A = {-1, 1, 2, 3} and B = {1, 4, 9}**

It is given that f: A → B: f(x) = x^{2} Ɐ x ∈ A

Each element in A has unique image in B where f is a function from A to B

**By substituting the values**

f(-1) = (-1)^{2} = 1

f(1) = 1^{2} = 1

f(2) = 2^{2} = 4

f(3) = 3^{2} = 9

**Here, two elements -1 and 1 have same image 1 ∈ B**

**Hence, f is many-one.**