(1) 2(a-4)(a+3)-(2a-1)(a-1)
=2a²-2a-24-2a²+3a-1
=a-25
(2) 5(y-x)³×3x³(x-y)六次方
=5(y-x)³×3x³(y-x)六次方
=15x³(y-x)九次方