622 
MEMORIAS CIENTIFICAS I LITERARIAS 
d X 
25. / — dx 
x + Lx 
Lx 
d L X 
L X 
- L (L X) 
26. /■ 
d X 
X (1 + L^x) J 1 + L 
^ dLx 
"" T~ ; T •> " = ^ ^ 
J 1 + L-x 
(J., Tannery, II, 519) 
Trigonometricas : 
27. d y = cos X d x = d sen X . • . /cos x d x = sen x. 
28. y sen x cos x =y^ sen x d sen x = sen" x 
dSerret, II, 77) 
29. J sen’f^ x cos x = J d n 
seni^^ + i X 
m + 1 
(Sturm, I, 362) 
30. /x (cos X + sen x cos x) ^ / [ (1 + sen x) cos x ] d x 
= /(l + sen x) d (1 + sen x) = — (1 + senx)” 
31. d y = sec2x dx = d tg X . • . / sec"x d x tg x 
f cosx , C dsenx , 
32. / d X == / •— — — - L sen x . (Pauly, 193) 
J senx J senx 
