Combined Variation

Variation relation

Equation form

y varies directly as w and the cube of x, and inversely as the cube root of z,

Variation relation

Definition graph of y against x

A graph with variable y at the vertical axis and variable x at the horizontal axis

Constant, k

A fixed or unchanged quantity value

The relationship ‘y varies directly as x’ can also be written as...

The relationship ‘x and y are directly proportional’ can also be written as...

Meaning of Symbol ∝ in (y ∝ x)

Refers to ‘is proportional to’

Examples of direct and joint variation relationships, y α xz

y changes directly with x and z

A joint variation

A variable changes directly and/or inversely with other variables

The equation Y changes directly with X and inversely with Z

Equation

Graph of y against x

Graph