**dy/dx****as rate measurer**;

*, if any two of*

**dy/dx=(dy/dt)/(dx/dt)***,*

**dy/dx***and*

**dy/dt***are*

**dx/dt**given the value of the third can be determined

For working out problems there will be two variables

*and*

**x***. From given condition a relation between*

**y***and*

**x***can be found and differentiating this expression we can find*

**y***,*

**dy/dx**Either

*or*

**dy/dt***is given*

**dx/dt**Thus if

*is given we can find*

**dy/dt***and vice versa .*

**dx/dt**If there is only one variable and its rate of change is given , then we can find the value of the variable in term of time

*by integrating this expression .*

**t**We already know that ;

**dy/dx=(dy/dt)/(dx/dt)=rate of change of (y)/rate of change of (x)**thus differential coefficient of

*with respect to*

**y***is equal to the ratio of the rate of change of*

**x***and rate of change of*

**y***.*

**x**