先化解，再求值

这是一道典型的二元二次多项式求解题
解:
-8x^2-[5y-3(2x^2-3y)+15]
=-8x^2-[5y-6x^2+9y+15]
=-8x^2-5y+6x^2-9y-15
=-2x^2-14y-15

将x=1 y=2代入-2x^2-14y-15
得-2+28-15=-41

谢谢

-8x^2-[5y-3(2x^2-3y)+15]
=-8x^2-5y+3(2x^2-3y)-15
=-8x^2-5y+6x^2-9y-15
=-2x^2-14y-15

x=-1,y=-2
-8x^2-[5y-3(2x^2-3y)+15]
=-2+28-15
=11

-8x^2-[5y-3(2x^2-3y)+15]
=-2x^2+4y-15
=-2-8-15
=-25