(x+2y)(x-2y)+3(x-2y)=0这个要怎么化简,

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(x+2y)(x-2y)+3(x-2y)=0这个要怎么化简,
(x+2y)(x-2y)+3(x-2y)=0这个要怎么化简,

(x+2y)(x-2y)+3(x-2y)=0这个要怎么化简,
(x+2y)(x-2y)+3(x-2y)=0
(x-2y)(x+2y+3)=0
所以x=2y或x=-2y-3

先将前面相乘算出,在再合并同类项,利用十字相乘法算出!!!!

(x+2y)(x-2y)+3(x-2y)=0
x^2-4y^2+3x-6y=0
(x+3/2)^2-(2y+3/2)^2=9/2

(x+2y)(x-2y)+3(x-2y)=0
所以(x+2y+3)(x-2y)=0
所有x+2y+3=0或x-2y=0
由两试得到x=-1.5 y=-0.75
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