a) xy²(2x - 3xy + y) + 1/4x²y(1/2y² - 8y)=2x²y²-3x²y³+xy³+1/8x²y³-2x²y²=-2 7/8 x²y³+xy³
b) -1/2x³y(xy - 2xy²) - 1/8xy²(4x³ - 16x²y)=[tex]-1/2x^4y^2+x^4y^3-1/2x^4y^2+2x^3y^3=-x^4y^2+x^4y^3+2x^3y^3[/tex]
c) -1/4x²y(-2x + y) - 3/4y(x² - x²y) - 1/2(x³y + xy)=1/2x³y-1/4x²y²-3/4x²y+3/4x²y²-1/2x³y-1/2xy=1/2x²y²-3/4x²y-1/2xy
