初一数学题!!!!!!!!!!!!急!!!!!!!!!!!!!!!!!!!!!!!!!!!
2个回答
展开全部
(1) x^2-y^2=5^2-3^2=25-9=16
(x+y)(x-y)=(5+3)(5-3)=16
(2) x^2-y^2=(1/2)^2-(1/3)^2=1/4-1/9=9/36-4/36=5/36
(x+y)(x-y)=(1/2+1/3)(1/2-1/3)=(3/6+2/6)(3/6-2/6)=(5/6)*(1/6)=5/36
发现的结论是x^2-y^2=(x+y)(x-y)
2014^2-2013^2=(2014+2013)(2014-2013)=4027*1=4027
(x+y)(x-y)=(5+3)(5-3)=16
(2) x^2-y^2=(1/2)^2-(1/3)^2=1/4-1/9=9/36-4/36=5/36
(x+y)(x-y)=(1/2+1/3)(1/2-1/3)=(3/6+2/6)(3/6-2/6)=(5/6)*(1/6)=5/36
发现的结论是x^2-y^2=(x+y)(x-y)
2014^2-2013^2=(2014+2013)(2014-2013)=4027*1=4027
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