100.2×99.8用平方差計算等於多少要步驟

100.2×99.8用平方差計算等於多少要步驟


100.2*99.8
=(100+0.2)*(100-0.2)
=100*100-0.2*0.2
=10000-0.04
=9999.96



運用平方差計算..
(-x+y)(-x-y)
(-x+y)(x+y)


這是要幹啥?
=x^2-y^2
=y^2-x^2



利用平方差的公式計算
7×2004-7×2000-7×3


=7*(2004-2000-3)
=7



運用平方差計算下列各題
(a-b+c-d)(a+b-c-d);(3a+b-2)(3a-b+2)


(a-b+c-d)(a+b-c-d)=[(a-d)-(b-c)][(a-d)+(b-c)]=(a-d)²;-(b-c)²;=a²;+b²;+c²;+d²;-2ad+2bc(3a+b-2)(3a-b+2)=[3a+(b-2)][3a-(b-2)]=9a²;-(b-2)²;=9a²;-b& sup2;+4b-4