(x-y)2+______=(x+y)2.
题型:填空题难度:一般来源:不详
(x-y)2+______=(x+y)2. |
答案
(x+y)2=x2+2xy+y2, =x2+2xy+y2-4xy+4xy, =x2-2xy+y2+4xy, =(x-y)2+4xy, 故(x-y)2+4xy=(x+y)2. |
举一反三
若y(x-1)-x(y-1)=5,则-xy=______. |
若Rt△ABC的三边长分别为a,b,c,且a,b满足a2-6a+b2-8b+25=0,那么边c的长为______. |
若(a-2b)2=a2+Kab+4b2,则K=______;若x2+kx+1是一个完全平方式,则k=______. |
(a+b)2=______+(a-b)2,(a+b)2+(a-b)2=______. |
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