When one quantity varies with respect to two or more quantities, we have a combined variation. When one quantity varies directly with two or more quantities, we have a joint variation.
z=5xy
Practice makes perfect
When one quantity varies with respect to two or more quantities, we have a combined variation. When one quantity varies directly with two or more quantities, we have what is called a joint variation.
Combined Variation
Equation Form
z varies jointly with x and y.
z=k x y
z varies jointly with x and y, and inversely with w.
z=k x y/w
z varies directly with x and inversely with the product w y.
z=k x/w y
In our exercise, we are told that z varies jointly with x and y.
z=k x y
Here k is the constant of variation, and it cannot equal 0. To find k we will substitute x= 3, y= 2, and z= 30 in the above equation.
