d: \(\left(x-2\right)\left(-x^2+x+4\right)\)
\(=-x^3+x^2+4x+2x^2-2x-8\)
\(=-x^3+3x^2+2x-8\)
e: \(\left(x^2-1\right)\left(x^2+2x\right)\)
\(=x^2\cdot x^2+x^2\cdot2x-1\cdot x^2-1\cdot2x\)
\(=x^4+2x^3-x^2-2x\)
f: \(\left(2x-1\right)\left(3x+2\right)\left(3-x\right)\)
\(=\left(6x^2+4x-3x-2\right)\left(-x+3\right)\)
\(=\left(6x^2+x-2\right)\left(-x+3\right)\)
\(=-6x^3+18x^2-x^2+3x+2x-6\)
\(=-6x^3+17x^2+5x-6\)
g: \(\left(x+3\right)\left(x^2+3x-5\right)\)
\(=x^3+3x^2-5x+3x^2+9x-15\)
\(=x^3+6x^2+4x-15\)
h: \(\left(xy-2\right)\left(x^3-2x-6\right)\)
\(=x^4y-2x^2y-6xy-2x^3+4x+12\)
i: \(\left(5x^3-x^2+2x-3\right)\left(4x^2-x+2\right)\)
\(=20x^5-5x^4+10x^3-4x^4+x^3-2x^2+8x^3-2x^2+4x-12x^2+3x-6\)
\(=20x^5-9x^4+19x^3-14x^2+7x-6\)
j: (8x+5y)(x-3)
\(=8x\cdot x-8x\cdot3+5y\cdot x-5y\cdot3\)
\(=8x^2-24x+5xy-15y\)
k: \(\left(x^2+2x+x^2-4\right)\left(x+y\right)\)
\(=\left(2x^2+2x-4\right)\left(x+y\right)\)
\(=2x^3+2x^2y+2x^2+2xy-4x-4y\)
