Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
f′(x)   =   (sec^2 x)etanx

Example 7: Find the second derivative of f (x) = ex


2
.

f′(x)   =   2xex

2

f′′(x)  =   2   ex

2
+ 4x^2 ex

2

Once again, it’s just a matter of following a formula.


THE DERIVATIVE OF loga x


This derivative is actually a little trickier than the derivative of a natural log. First, if you remember your
logarithm rules about change of base, we can rewrite loga x.


loga x  =   

Review the unit on Prerequisite Mathematics if this leaves you scratching your head. Anyway, because ln
a is a constant, we can take the derivative.


This leads us to our next rule.


Rule    No. 5:  If  y   =   logax,  then    

Once again, incorporating the Chain Rule gives us a more useful formula.


Rule    No. 6:  If  y   =   logau,  then    

Example 8: Find the derivative of f(x) = log 10 x.


f′(x)   =   
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