Derivative check please! Its been a while since trying to take a derivative. I watched a clip where the instructor says that : $$\frac{ d }{ dr }\frac{ a }{ (1-r) } = \frac{ a }{ (1-r)^2 }$$

where a is a constant. If I am remembering derivatives correctly, shouldn't this be $$-\frac{ a }{ (1-r)^2 }$$ ?

Question

Derivative check please! Its been a while since trying to take a derivative. I watched a clip where the instructor says that : $$\frac{ d }{ dr }\frac{ a }{ (1-r) } = \frac{ a }{ (1-r)^2 }$$ 

where a is a constant. If I am remembering derivatives correctly, shouldn't this be $$-\frac{ a }{ (1-r)^2 }$$ ?

anonymous · Answer

My impression is that the (1-r) is to the negative 1 power.. and when you take the derivative you "power down" to -2 and put a -1 out front?

isaiah.feynman · Answer

attachment

isaiah.feynman · Answer

Sorry for the messy writing. I'm using the pad on my laptop.

anonymous · Answer

Thank you!