Rational Expressions

Question 1

Direct Variation

Answer 1

A variable “y” varies directly with a variable “x” if the ratio y/x remains constant.
y varies directly with x if we have the following:
y = kx
for some (nonzero) constant k

Question 2

Inverse variation

Answer 2

variable y varies inversly with a variable x if the “product: yx” remains constant.
y varies inversely with x if:
y = k/x
for some (nonzero) constant k

Question 3

Joint variation

Answer 3

a variable y varies jointly with variables x and z if the ratio y/xz remains constant
y varies jointly with x and z if:
y = kxz
for some (nonzero) constant k