1) $x^3 - 5x^2 + 10x - 8
$= (x^3 - 8) - (5x^2 - 10x)$
$= (x-2)(x^2 + 2x + 4) - 5x(x - 2)$
$= (x -2)(x^2 + 2x + 4 -5x)$
$= (x-2)(x^2 -3x + 4)$
2) $6x^2 - 11x + 3$
$= 6x^2 - 2x - 9x + 3$
$= 6x(3x -1) - 3(3x -1)$
$= (3x -1)(6x -3)$
$= 3(3x -1)(2x -1)$
3) $x^3 + 2x - 3$
$= x^3 - x^2 + x^2 - x + 3x - 3$
$= x^2(x -1) + x(x -1) + 3(x -1)$
$= (x -1)(x^2 + x + 3)$
4) $4x^2.4x^2 + y^2.y^2$
$= 4x^2.4x^2 + 2.4x^2.y^2 + y^2.y^2 - 2.4x^2.y^2$
$= (4x^2 + y^2)^2 - (2\sqrt2xy)^2$
$= (4x^2 - 2\sqrt2xy + y^2)(4x^2 + 2\sqrt2xy + y^2)$