$a)x^4y^5\bigg(\dfrac{7}{3}x^2y^4-\dfrac{1}{7}x^3y-\dfrac{5}{14}\bigg)$
$=\dfrac{7}{3}x^6y^9-\dfrac{1}{7}x^7y^6-\dfrac{5}{14}x^4y^5$
$b)(3x+5)(2x-7)$
$=6x^2-21x+10x-35$
$=6x^2-11x-35$
$c)(-5x+2)(-3x-4)$
$=15x^2+20x-6x-8$
$=15x^2+14x-8$
$d)(x-5)^2-(4x-3)(2-x)$
$=x^2-10x+25-8x+4x^2+6-3x$
$=5x^2-21x+31$
$e)(x-5)(-x^2+x+1)+x^3$
$=-x^3+x^2+x+5x^2-5x-5+x^3$
$=6x^2-4x-5$
$f)(x^2-2x-1)(x-3)-x(x-2)(x+2)$
$=x^3-3x^2-2x^2+6x-x+3-x(x^2-4)$
$=x^3-3x^2-2x^2+6x-x+3-x^3+4x$
$=-5x^2+9x+3$
$g)(-x+4)(-x^2+4x-1)$
$=x^3-4x^2+x-4x^2+16x-4$
$=x^3-8x^2+17x-4$
