Mikä on (dx) / (x.sqrt (x ^ 3 + 4)): n integraatio?

Mikä on (dx) / (x.sqrt (x ^ 3 + 4)): n integraatio?
Anonim

Vastaus:

# 1/6 ln | {sqrt (x ^ 3 + 4) -2} / {sqrt (x ^ 3 + 4) +2} | + C #

Selitys:

korvike # X ^ 3 + 4 = u ^ 2 #. Sitten # 3x ^ 2DX = 2udu #, jotta

# dx / {x sqrt {x ^ 3 + 4}} = {2udu} / {3x ^ 3u} = 2/3 {du} / (u ^ 2-4) = 1/6 ({du} / {u -2} - {du} / {u + 2}) #

Täten

#int dx / {x sqrt {x ^ 3 + 4}} = 1/6 int ({du} / {u-2} - {du} / {u + 2}) = 1/6 ln | {u- 2} / {u + 2} | + C #

# = 1/6 ln | {sqrt (x ^ 3 + 4) -2} / {sqrt (x ^ 3 + 4) +2} | + C #