Question

3a²-2ab+2b²怎么化简

化简（a²-2ab+2b²)-(2a²-2ab-3ab²)
急求 麻烦大家了
还有这道 (4x²-3y²)-[2(x²-1)+2y²-3]
化简求值：5a²b-[2a²b-3(abc-ac²)-5ac]-4abc.其中a=-3，b=4，c=-1

Answer 1

(a²-2ab+2b²粗唤)-(2a²-2ab-3ab²)
=a²-2ab+2b²-2a²+2ab+3ab²
=2b²+3ab²-a²
=(2+3a)b²-a²
=(b*(2+3a)^0.5-a)(b*(2+3a)^0.5+a)
(4x²-3y²)-[2(x²-1)+2y²-3]
=4x²-3y²-2(x²灶凳粗-1)-2y²+3
=4x²-3y²-2x²+2-2y²+3
=2x²-5y²+5
化简求值：5a²b-[2a²b-3(abc-ac²)-5ac]-4abc.其中隐镇a=-3,b=4,c=-1
5a²b-[2a²b-3(abc-ac²)-5ac]-4abc
=5a²b-2a²b+3(abc-ac²)+5ac-4abc
=5a²b-2a²b+3abc-3ac²+5ac-4abc
=3a²b-abc+5ac-3ac²
=ab(3a-c)+ac(5-3c)
=a(b(3a-c)+c(5-3c))
=(-3)(4(3(-3)-(-1))+(-1)(5-3(-1))
=(-3)(4((-9)+1)-(5+3)
=(-3)(4*(-8))-8
=96-8
=88