③(x-2y)(2x+4y)④-2a²(½ab+b²)-5a(a²b-ab²)
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![③(x-2y)(2x+4y)④-2a²(½ab+b²)-5a(a²b-ab²)](/uploads/image/z/1084809-57-9.jpg?t=%E2%91%A2%EF%BC%88x-2y%EF%BC%89%EF%BC%882x%EF%BC%8B4y%EF%BC%89%E2%91%A3-2a%26%23178%3B%EF%BC%88%26%23189%3Bab%EF%BC%8Bb%26%23178%3B%EF%BC%89-5a%EF%BC%88a%26%23178%3Bb-ab%26%23178%3B%EF%BC%89)
③(x-2y)(2x+4y)④-2a²(½ab+b²)-5a(a²b-ab²)
③(x-2y)(2x+4y)④-2a²(½ab+b²)-5a(a²b-ab²)
③(x-2y)(2x+4y)④-2a²(½ab+b²)-5a(a²b-ab²)
③(x-2y)(2x+4y)
=2(x-2y(x+2y)
=2x²-8y²
④-2a²(½ab+b²)-5a(a²b-ab²)
=-a²b(a+2b)-5a²b(a-b)
=a²b[-(a+2b)-5(a-b)]
=a²b(-a-2b-5a+5b)
=a²b(-6a+3b)
=-6a³b+3a²b²
什么意思的