当x=2,y=1÷2时,化简代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值
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![当x=2,y=1÷2时,化简代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值](/uploads/image/z/4335781-13-1.jpg?t=%E5%BD%93x%3D2%2Cy%3D1%C3%B72%E6%97%B6%2C%E5%8C%96%E7%AE%80%E4%BB%A3%E6%95%B0%E5%BC%8F%28x%2By%29%28x-y%29%2B%28x-y%29%26sup2%3B-%28x%26sup2%3B-3xy%29%E7%9A%84%E5%80%BC)
当x=2,y=1÷2时,化简代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值
当x=2,y=1÷2时,化简代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值
当x=2,y=1÷2时,化简代数式(x+y)(x-y)+(x-y)²-(x²-3xy)的值
原式=(X+Y+X-Y)(X-Y)-X(X-3Y)=X(2X-2Y-X+3Y)=x²+XY=5
(x+y)(x-y)+(x-y)²-(x²-3xy)
=x²-y²+x²-2xy+y²-x²+3xy
=x²+xy
=x(x+y) 把x=2,y=1/2代入
=2(2+1/2)=5