# Check the answer of a differential equation when I put it in Wolfram Alpha?

GROUPS:
 jorge aldape 1 Vote This: y'''+4y'=sec2x http://www.wolframalpha.com/input/?i=y%27%27%27%2b4y%27=sec2xbrings me this answer:So the circled with red it's incorrect in my opinionProbably the first mistake causes the second.What do you think?
 Doing this in three steps to get it to fit within the line length limitationIf the supposed solution to the DE is C1 Sin[2x]+C2 Cos[x]^2+C3-x Cos[2x]/4-Log[Cos[x]-Sin[x]]/8+Log[Sin[x]+Cos[x]]/8+Sin[2x]Log[Cos[2x]]/8 then the third derivative seems to bethirdwhich is also -(Sec[2 x] (-2+8 C1+Log[Cos[2 x]]+Cos[4 x] (8 C1+Log[Cos[2 x]])+2 (-2 C2+x) Sin[4 x]))/2 and four times the first derivative seems to befourfirstwhich is also Cos[2 x] (8 C1+Log[Cos[2 x]])+2 (-2 C2+x) Sin[2 x] and the sum of those seems to besumwhich is also Sec[2 x] Can you explain exactly where in these steps you seem to see an error and what the error seems to be?