化简 1.(x²—y²—2xy)—3(—x²+xy)—2(x²—5/2xy)
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![化简 1.(x²—y²—2xy)—3(—x²+xy)—2(x²—5/2xy)](/uploads/image/z/3738096-0-6.jpg?t=%E5%8C%96%E7%AE%80+1.%EF%BC%88x%26%23178%3B%E2%80%94y%26%23178%3B%E2%80%942xy%EF%BC%89%E2%80%943%EF%BC%88%E2%80%94x%26%23178%3B%2Bxy%EF%BC%89%E2%80%942%EF%BC%88x%26%23178%3B%E2%80%945%2F2xy%EF%BC%89)
化简 1.(x²—y²—2xy)—3(—x²+xy)—2(x²—5/2xy)
化简 1.(x²—y²—2xy)—3(—x²+xy)—2(x²—5/2xy)
化简 1.(x²—y²—2xy)—3(—x²+xy)—2(x²—5/2xy)
(x²—y²—2xy)—3(—x²+xy)—2(x²—5/2xy)
=x²-y²-2xy+3x²-3xy-2x²+5xy
=(x²+3x²2x²)-y²-(2xy+3xy-5xy)
=2x²-y²
(x²—y²—2xy)—3(—x²+xy)—2(x²—5/2xy)
=x²-y²-2xy+3x²-3xy-2x²+5xy
=2x²-y²
(X-y)2-2y2+3x2-3xy-2x2+5xy
=(X-y)2-2y2-x2+2xy
=(X-y)2-y2-x2+2xy-y2
=(X-y)2-(y2+x2-2xy)-y2
=(X-y)2-(X-y)2-y2
=-y2
原式=x²-y²-2xy+3x²-3xy-2x²+5xy
=2x²-y²