lim (x → 0) SIN(pi·x^2)^2/x^4
lim (x → 0) (SIN(pi·x^2)/x^2)^2
Wir kümmern uns zunächst um den Grenzwert
lim (x → 0) SIN(pi·x^2)/x^2
L'Hospital
lim (x → 0) 2·pi·x·COS(pi·x^2)/(2·x)
lim (x → 0) pi·COS(pi·x^2) = pi
Also
lim (x → 0) (SIN(pi·x^2)/x^2)^2 = pi^2