a) \(x\left(2x^2-3x+2\right)=2x^3-3x^2+2x\)
b) \(\left(2x^2\right).\left(x-x^2+3\right)=2x^3-2x^4+6x^2\)
\(=-2x^4+2x^3+6x^2\)
c) \(\left(x^2-5x-1\right).\left(-3x\right)^3=\left(x^2-5x-1\right).\left(-27x^3\right)\)
\(=-27x^5+135x^4+27x^3\)
d) \(\left(x^2-2x-1\right).\left(\frac{1}{2}x\right)^2=\left(x^2-2x-1\right).\frac{1}{4}x^2\)
\(=\frac{1}{4}x^4-\frac{1}{2}x^3-\frac{1}{4}x^2\)