(你式子中y^应该是y^2,如果是y^n,则解答中的y^2全部换为y^n)
(9/2x应该是9x/2)
原式=x/2-2[x-(y^2)/3-y^2/6+9x/12]
=x/2-2x+2(y^2)/3+2(y^2)/6-9x/6
=3x/6-12x/6-9x/6+4(y^2)/6+2(y^2)/6
=-18x/6+6(y^2)/6
=-3x+y^2
(你式子中y^应该是y^2,如果是y^n,则解答中的y^2全部换为y^n)
(9/2x应该是9x/2)
原式=x/2-2[x-(y^2)/3-y^2/6+9x/12]
=x/2-2x+2(y^2)/3+2(y^2)/6-9x/6
=3x/6-12x/6-9x/6+4(y^2)/6+2(y^2)/6
=-18x/6+6(y^2)/6
=-3x+y^2