-0.6*(-9)^4+1.9*(-9)^2-4
по действиям

-0.6·(-9)⁴+1.9·(-9)²-4=(-9)²·(-0.6·(-9)²+1.9)-4= =81·(-0.6·81+1.9)-4=81·(-48.6+1.9)-4=81·(-46.7)-4=-3786.7