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若4x^2-4x+9y^2-12y+5=0,求(x-3y)^2-(x+3y)^2
人气:188 ℃ 时间:2020-02-03 17:40:18
解答
4x^2-4x+9y^2-12y+5=04x^2-4x+1+9y^2-12y+4=0(2x-1)^2+(3y-2)^2=0所以2x-1=0x=1/23y-2=0y=2/3(x-3y)^2-(x+3y)^2=(x-3y+x+3y)(x-3y-x-3y)=2x*(-6y)=-12xy=-12*1/2*2/3=-4
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