2x二次方-1/2【6-2（x二次方-2）】,其中x=-2.
2x二次方-1/2【6-2（x二次方-2）】
=2x²-1/2(6-2x²+4)
=2x²+x²-5
=3x²-5
=3×4-5
=7
-2x二次方-1/2【3y二次方-2（x二次方-y二次方）+6】,其中x=-2,y=-0.5.
-2x二次方-1/2【3y二次方-2（x二次方-y二次方）+6】
=-2x²-1/2(3y²-2x²+2y²+6)
=-2x²-5/2y²+x²-3
=-x²-5/2y²-3
=-4-5/8-3
=-7又5/8
5ab二次方-｛2a二次方b-【3ab二次方-（4ab二次方-2ab二次方）】｝,其中a、b满足条件（3a+2）二次方+丨2b+3丨=0.
（3a+2）二次方+丨2b+3丨=0.
则,3a+2=0且2b+3=0
解得 a=-2/3 ,b=-3/2
5ab二次方-｛2a二次方b-【3ab二次方-（4ab二次方-2ab二次方）】｝
=5ab²-[2a²b-(3ab²-2ab²)]
=5ab²-2a²b+ab²
=6ab²-2a²b
=2ab(3b-a)
=2×(-2/3)×(-3/2)×(-9/2+2/3)
=-7又2/3