已知A=4a²+3b²-5ab,B=3ab-2a²+3b²(1)求:3A-2B(2)当a=-2,b=1时,求3A-2B的值
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/14 14:40:21
![已知A=4a²+3b²-5ab,B=3ab-2a²+3b²(1)求:3A-2B(2)当a=-2,b=1时,求3A-2B的值](/uploads/image/z/5339710-46-0.jpg?t=%E5%B7%B2%E7%9F%A5A%3D4a%26%23178%3B%2B3b%26%23178%3B-5ab%2CB%3D3ab-2a%26%23178%3B%2B3b%26%23178%3B%EF%BC%881%EF%BC%89%E6%B1%82%EF%BC%9A3A-2B%EF%BC%882%EF%BC%89%E5%BD%93a%3D-2%2Cb%3D1%E6%97%B6%2C%E6%B1%823A-2B%E7%9A%84%E5%80%BC)
x){}KmMՔ
- ]$'[$]#t{:|YƎFN@#ӽmutl
MߦT }>i"}Ĵ&Lf;V[cVہtvpB'DQb!PeRXHOO(ff54U'44ќ(3m#mcfK=<;hـ9FH :
已知A=4a²+3b²-5ab,B=3ab-2a²+3b²(1)求:3A-2B(2)当a=-2,b=1时,求3A-2B的值
已知A=4a²+3b²-5ab,B=3ab-2a²+3b²
(1)求:3A-2B
(2)当a=-2,b=1时,求3A-2B的值
已知A=4a²+3b²-5ab,B=3ab-2a²+3b²(1)求:3A-2B(2)当a=-2,b=1时,求3A-2B的值
(1)3A-2B
=3(4a²+3b²-5ab)-2(3ab-2a²+3b²)
=12a^-15ab+9b^
..+4a^-6ab-6b^
=16a^-21ab+3b^,
(2)当a=-2,b=1时,3A-2B
=64+42+3
=109.
25