初一数学题 20分...
来源:百度知道 编辑:UC知道 时间:2024/06/28 06:05:20
用简便方法计算: 要过程
1. (a²+1)²(a-1)²(a+1)²
2. (x-y+2)(x+y-2)
1. (a²+1)²(a-1)²(a+1)²
2. (x-y+2)(x+y-2)
(a²+1)²(a-1)²(a+1)²
=(a²+1)²[(a-1)(a+1)]²
=[(a²+1)(a²-1)]²
=[a^4-1]^2
=a^8-2a^4+1
2.(x-y+2)(x+y-2)
=[x-(y-2)][x+(y-2)]
=x^2-(y-2)^2
=x^2-y^2+4y-4
1.=(a²+1)²(a²-1)²
=(a²-1)四次方
2.=x²-y²-4
都是平方差公式
1. (a²+1)²(a-1)²(a+1)²
= (a²+1)²(a²-1)²
=(a^4-1)^2
=a^8-2a^4+1
2. (x-y+2)(x+y-2)
=x^2-(y-2)^2
=x^2-y^2+4y-4
1 (a^2+1)^2*[(a-1)*(a+1)]^2=(a^2+1)^2*(a^2-1)^2=(a^4-1)^2
2 [x+(y-2)]*[x-(y-2)]=x^2-(y-2)^2
1.可以这样拆:(a-1)(a+1)(a-1)(a+1)(a²+1)(a²+1)=(a²-1)(a²+1)(a²-1)(a²+1)=(a^4+1)²
2.这样拆:(x-(y-2))(x+(y-2))=x²-(y-2)²