Simplifying after applying quotient rule

[en bloc]

Homework Statement

http://images.calcchat.com/solutionart/etf5e/03/c/se03c01047.png

Homework Equations

The Attempt at a Solution

What am i missing, because i get: 6/4 [(-1 + tanx*secx- (tanx)^2]

 

[ehild]

Use that sin^2x+cos^x=1 in the third row .

ehild