化简求值:-(2a2-ab+3b2)+[3a2-2(a2+3ab)-b2],其中a=-2,b=-

化简求值:-(2a2-ab+3b2)+[3a2-2(a2+3ab)-b2],其中a=-2,b=-1
2025-02-25 15:56:56
推荐回答(1个)
回答1:

-(2a2-ab+3b2)+[3a2-2(a2+3ab)-b2]
=-2a2+ab-3b2+3a2-2a2-6ab-b2
=-a2-5ab-4b2
当a=-2,b=-1时,
原式=-(-2)2-5×(-2)×(-1)-4×(-1)2
=-18.