Final answer:
The equations that represent a cylinder in space are x² + y² = z = 2 and z = xy.
Step-by-step explanation:
To represent a cylinder in space, the equation must have two variables and describe a relationship that forms a cylindrical shape. Looking at the given options:
a) y = ln(z) - This equation involves the natural logarithm of z and does not have two variables. It does not represent a cylinder.
b) y = cos(x) - This equation involves the cosine function and only has one variable. It does not represent a cylinder.
c) z = sin(y) - This equation involves the sine function and only has one variable. It does not represent a cylinder.
d) xy = 8 - This equation has two variables and represents a rectangular hyperbola, not a cylinder.
e) x² + y² = z = 2 - This equation involves two variables and represents a cylinder with a radius of 2.
f) z = xy - This equation has two variables and represents a cylinder.
Therefore, the equations that represent a cylinder in space are x² + y² = z = 2 and z = xy.