已知x=75分之22,y=44分之25,求(x+y)平方-(x-y)平方的值,

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已知x=75分之22,y=44分之25,求(x+y)平方-(x-y)平方的值,

已知x=75分之22,y=44分之25,求(x+y)平方-(x-y)平方的值,
已知x=75分之22,y=44分之25,求(x+y)平方-(x-y)平方的值,

已知x=75分之22,y=44分之25,求(x+y)平方-(x-y)平方的值,
(x+y)2 -(x-y)2
=(x2+y2+2xy)-(x2+y2-2xy)
=2xy+2xy
=4xy
=4*(22/75)*(25/44)
=2/3
(说明:字母和括号后面的2是平方)

(x+y)²-(x-y)²
=(x+y-x+y)(x+y+x-y)
=2y*2x
=4xy
=4*22/75*25/44
=4*22*25/75*44
=2*2*22*25/3*25*44
=2/3

(x+y)平方-(x-y)平方
=4xy
=4*22/75*25/44
=2/3

(x+y)^2-(x-y)^2=(x+y+x-y)(x+y-x+y)=4x*y=4*22/75*25/44=2/3

(x+y)^2-(x-y)^2=[(x+y)-(x-y)][(x+y)+(x-y)]=4xy=4*22/75*25/44=4*1/3*1/2=2/3