Xigsinta labaad waa xigidda xigsinta koowaad/ raadi derivative-ka derivative-kii hore ee aad soo saartay, haddaba:
– Raadi xigsinta fansaarka
– Kaddibna, sii xig isla xigsintaas.
Xigsinta koowaad waxa ay nasiisaa tiirada xoodka(slope of the curve).
Xigsinta labaadna waxa ay noo sheegtaa golxanaanta(concavity-ga) oo aynu dib ka baran doonno.
Xigsinta koowaad waxaa u summad ah in xarriiq yar dusha laga saaro f'(x).
Xigsinta labaad waxaa u summad ah in labo xarriiq oo yar-yar dusha laga saaro f”(x).
Tusaale 1: Raadi xigsinta 2aad ee f(x)=x^{3}
Furfuris {solution):
f'(x)=3x^{(3-1)}
f'(x)=3x^{2}
Si aynu u helno xigsinta labaad, waxa aynu sii xigaynaa f'(x)=3x^{2}
f''(x)=2\times3x^{(2-1)}
f''(x)=6x
Tusaale 2: find \frac{d^{2}y}{dx^{2}} of y= x^{3}+12x^{2}+x+12
Furfuris {solution):
\frac{dy}{dx}= 3 x^{2}+24x+1
\frac{d^{2}y}{dx^{2}} = 6x+24