一道初一代数题已知x满足(x-5)^2+(6-x)^2=4,则(x-5)乘(6-x)等于几过程要详细
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一道初一代数题已知x满足(x-5)^2+(6-x)^2=4,则(x-5)乘(6-x)等于几过程要详细
一道初一代数题
已知x满足(x-5)^2+(6-x)^2=4,则(x-5)乘(6-x)等于几
过程要详细
一道初一代数题已知x满足(x-5)^2+(6-x)^2=4,则(x-5)乘(6-x)等于几过程要详细
等于-1.5
(x-5)^2+(6-x)^2=x^2-10x+25+36-12x+x^2=2x^2-22x+61=4
即:x^2-11x=(4-61)/2=-28.5
则:(x-5)(6-x)=6x-x^2-30+5x=-x^2+11x-30=28.5-30=-1.5
[(x-5)+(6-x)]^2=(x-5)^2+2(x-5)(6-x)+(6-x)^2=1
所以2(x-5)(6-x)=-3
(x-5)(6-x)=-3/2
配方法,-3/2
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