Variations

Variations

In our daily life we come across many situations wherein if there are two quantities, if one increase the other increase or vice-versa.  If one quantity decreases other quantity decreases.
For any two quantities x and y, if the value of y increases with an increase in the value of x such that x/y remains constant, then the two quantities x and y are said to be in direct proportion. Two quantities x and y in direct proportion are written
as x ∝ y.
Two quantities x and y are in direct proportion, then the ratio between the corresponding values of x and y is constant. Thus x₁/y₁ = x₂/y₂ = x₃/y₃ and so on.


For any two quantities x and y, if the value of y decreases with an increase in the value of x such that xy remains constant, the two quantities x and y are said to be in inverse proportion.
Two quantities x and y in inverse proportion are written as x ∝ 1/y. We can also say that if two quantities x and y are in inverse proportion, then the product of corresponding values of x and y is constant, thus, x₁y₁ = x₂y₂ = x₃y₃ and so on.