Tính các biểu thức (a) 2x(3x^2−5x+3). (b) (x−4y)(x^2−2xy+3).

a) \[2x\left( {3{x^2} - 5x + 3} \right)\]\[ = 6{x^3} - 10{x^2} + 6x\]

b) \[\left( {x-4y} \right)\left( {{x^2}-2xy + 3} \right)\]

\[ = {x^3} - 2{x^2}y + 3x - 4{x^2}y + 8x{y^2} - 12y\]

\[ = {x^3} - 6{x^2}y + 3x + 8x{y^2} - 12y\]

c) \(\left( {5{x^5}{y^4}z + \frac{1}{2}{x^4}{y^2}{z^3} - 2x{y^3}{z^2}} \right):\frac{1}{4}x{y^2}z\)

\( = \frac{5}{4}{x^4}{y^2} + 2{x^3}{z^2} - 8yz.\)

d) \(\left( {2x - 1} \right)\left( {4{x^2} + 2x + 1} \right)\)

\[ = 8{x^3} + 4{x^2} + 2x - 4{x^2} - 2x - 1.\]