问题
解答题
先化简,再求值:3a2+3(3b2+ab)-(9b2-2a2),其中a=-1,b=-2.
答案
3a2+3(3b2+ab)-(9b2-2a2),
=3a2+9b2+3ab-9b2+2a2,
=5a2+3ab,
当a=-1,b=-2,
3a2+3(3b2+ab)-(9b2-2a2)=5a2+3ab=11.
先化简,再求值:3a2+3(3b2+ab)-(9b2-2a2),其中a=-1,b=-2.
3a2+3(3b2+ab)-(9b2-2a2),
=3a2+9b2+3ab-9b2+2a2,
=5a2+3ab,
当a=-1,b=-2,
3a2+3(3b2+ab)-(9b2-2a2)=5a2+3ab=11.