2x^2+ax-y+6-(2bx^2-3x+5y)
=(2-2b)x^2+(a+3)x-6y+6
所以2-2b=0,a+3=0
即b=1,a=-3
1/3a^3-2b^2-(1/4a^3-3b^2)
=9-2-(1/4*(-27)-3)
=7+27/4+3
=10+27/4
=67/4
2x^2+ax-y+6-(2bx^2-3x+5y)
=(2-2b)x^2+(a+3)x-6y+6
所以2-2b=0,a+3=0
即b=1,a=-3
1/3a^3-2b^2-(1/4a^3-3b^2)
=9-2-(1/4*(-27)-3)
=7+27/4+3
=10+27/4
=67/4