\(a,=\dfrac{1}{2}x^2y.16x^4y^2=\dfrac{16}{2}x^6y^3=8x^6y^3\\ b,=\dfrac{4}{3}x^5-6x^4+2x^3-2x^4+9x^3-3x^2+\dfrac{2}{3}x^2-3x+1=\dfrac{4}{3}x^5-8x^4+11x^3-\dfrac{7}{3}x^2-3x+1\\ c,=2x^2y^2+3x^2y^3-x^3y^2+2x^3y^2+3x^3y^3-x^4y^2-2xy^3-3xy^4+x^3y^3=2x^2y^2+3x^2y^3+x^3y^2+4x^3y^3-2xy^3-x^4y^2-3xy^4\)
`a)1/2x^2y(-4x^2y)^2=1/2x^2y. 16x^4y^2=(1/2 .16)(x^2 .x^4)(y.y^2)=8x^6y^3`
`b)(2/3x^2-3x+1)(2x^3-3x^2+1)`
`=4/3x^5-2x^4+2/3x^2-6x^4+9x^3-3x+2x^3-3x^2+1`
`=4/3x^5-8x^4+11x^3-7/3x^2-3x+1`
`c)(2xy+3xy^2-x^2y)(xy+x^2y-y^2)`
`=2x^2y^2+2x^3y^2-2xy^3+3x^2y^3+3x^3y^3-3xy^4-x^3y^2-x^4y^2+x^2y^3`
`=2x^2y^2+x^3y^2-2xy^3+4x^2y^3+3x^3y^3-3xy^4-x^4y^2`
