If x = (a^2) / b, which situation would always double the value of x?

(1) Doubling the value of a

(2) Halving the value of a

(3) Doubling the value of b

(4) Halving the value of b

(4) Halving the value of b

Example #1:

a = 4, b = 2

x = (4^2) / 2

x = 16 / 2

x = 8

a = 4, b = 1

x = (4^2) / 1

x = 16 / 1

x = 16

Example #2:

a = 8, b = 4

x = (8^2) / 4

x = 64 / 4

x = 16

a = 8, b = 2

x = (8^2) / 2

x = 64 / 2

x = 32