If xy equals 20 then y decreases as x - decreases increases or stays constant?

Answer 1

linear

if xy = 20, then y = 20/x or y = 20(1/x)

So x can be positive or negative but not zero:

There are 3 cases:

Case 1:

if x = 20, then y is constant, y = 1.

Case 2:

a) if x > 0, and if x → 0+, then y → ∞ (if x decreases but not reaches zero, then y increases without end).

b) if x < 0 and if x → -∞, then y → 0 (if x decreases, then y increases and approaches to zero).

Case 3:

a) if x > 0 and if x → ∞, then y → 0 (if x increases, y decreases and approaches to zero)

b) if x < 0, and if x → 0-, then y → -∞ (if x increases but not reaches zero, then y decreases without end).