Show that dy/dx is +ve when a < x < b

I have a differentiation problem which starts with

I have to find dy/dx. No problem there, get

Then to find values of x where dy/dy = 0

But then it asks "Denoting the values of x which you have just calculated by a and b, where a < b, show dy/dx is positive when a < x < b".

I can see graphically where dy/dx is positive, but do I need to show algebraically? How would I answer this?

Angus

Re: Show that dy/dx is +ve when a < x < b

Quote:

Originally Posted by

**angypangy** I have a differentiation problem which starts with

I have to find dy/dx. No problem there, get

Then to find values of x where dy/dy = 0

But then it asks "Denoting the values of x which you have just calculated by a and b, where a < b, show dy/dx is positive when a < x < b".

I can see graphically where dy/dx is positive, but do I need to show algebraically? How would I answer this?

Angus

You want to find where

So the derivative is positive in between these values.