Spiegare gentilmente i ragionamenti, i passaggi e argomentare.
y = LN((√(x^2 + 1) + x)/(√(x^2 + 1) - x))
equivale a scrivere:
y = LN((√(x^2 + 1) + x)^2)
Quindi:
y' = dy/dx=
=D(2·LN(√(x^2 + 1) + x)=
=2·D(LN(√(x^2 + 1) + x)=
=2·D(√(x^2 + 1) + x)/(√(x^2 + 1) + x)=
=2·(D(x) + D(√(x^2 + 1)))/(√(x^2 + 1) + x)=
=2·(1 + D(√(x^2 + 1)))/(√(x^2 + 1) + x)=
=2·(1 + D(x^2 + 1)/(2·√(x^2 + 1)))/(√(x^2 + 1) + x)=
=2·(1 + (D(1) + D(x^2))/(2·√(x^2 + 1)))/(√(x^2 + 1) + x)=
=2·(1 + D(x^2)/(2·√(x^2 + 1)))/(√(x^2 + 1) + x)=
=2·(1 + 2·x/(2·√(x^2 + 1)))/(√(x^2 + 1) + x)=
=2·(√(x^2 + 1) - x)·(√(x^2 + 1) + x)/√(x^2 + 1)=
=2/√(x^2 + 1)
Procedendo in modo analogo ottieni:
y''=- 2·x/(x^2 + 1)^(3/2)