Đáp án:
$a,(\dfrac{1}{2} - 1)(2x-3)$
$ = x^2 - \dfrac{3}{2}x-2x +3$
$ = x^2-\dfrac{7}{2}x +3$
$b(x-7)(x-5)$
$ = x^2 -5x -7x +35$
$ = x^2 -12x +35$
$c, (x-\dfrac{1}{2})(x+\dfrac{1}{2})(4x-1)$
$ = (x^2-\dfrac{1}{4})(4x-1)$
$ = 4x^3 - x^2 -x +\dfrac{1}{4}$