Matsakaicin nau'i-nau'i na biquadratic aiki ne na digiri 4, wanda kuma aka sani da polynomial quartic. Yana aiki ne na sigar:f(x) = ax^4 bx^3 cx^2 dx einda a, b, c, d, da e suke. akai-akai, kuma x shine mai canzawa. Kalmar "biquadratic" ta fito ne daga gaskiyar cewa yawan adadin ya ƙunshi murabba'ai biyu (x^2) na m x.
