(1)原式=-1-0.5× 1 3 ×(-7)=-1+ 7 6 = 1 6 ;(2)原式=90°-40°39′+3°16′40″=93°16′40″-40°39′=52°37′40″;(3)原式=-4× 5 4 ×(- 1 20 )= 1 4 ;(4)原式=x3-2y3-3x2y-3x3+3y3+7x2y=(1-3)x3+(-2+3)y3+(-3+7)x2y=-2x3+y3+4x2y.