[(x-y)²+(x+y)²】(x²-y²) (m-n-3)² (x-2y+z)(-x+2y+z)乘法公式计算比较下列两数的大小:1995×1997与1993×1999
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![[(x-y)²+(x+y)²】(x²-y²) (m-n-3)² (x-2y+z)(-x+2y+z)乘法公式计算比较下列两数的大小:1995×1997与1993×1999](/uploads/image/z/1064305-1-5.jpg?t=%5B%28x-y%29%26%23178%3B%2B%EF%BC%88x%2By%29%26%23178%3B%E3%80%91%EF%BC%88x%26%23178%3B-y%26%23178%3B%EF%BC%89+%EF%BC%88m-n-3%29%26%23178%3B+%EF%BC%88x-2y%2Bz%29%28-x%2B2y%2Bz%29%E4%B9%98%E6%B3%95%E5%85%AC%E5%BC%8F%E8%AE%A1%E7%AE%97%E6%AF%94%E8%BE%83%E4%B8%8B%E5%88%97%E4%B8%A4%E6%95%B0%E7%9A%84%E5%A4%A7%E5%B0%8F%EF%BC%9A1995%C3%971997%E4%B8%8E1993%C3%971999)
[(x-y)²+(x+y)²】(x²-y²) (m-n-3)² (x-2y+z)(-x+2y+z)乘法公式计算比较下列两数的大小:1995×1997与1993×1999
[(x-y)²+(x+y)²】(x²-y²) (m-n-3)² (x-2y+z)(-x+2y+z)乘法公式计算
比较下列两数的大小:1995×1997与1993×1999
[(x-y)²+(x+y)²】(x²-y²) (m-n-3)² (x-2y+z)(-x+2y+z)乘法公式计算比较下列两数的大小:1995×1997与1993×1999
[(x-y)²+(x+y)²】(x²-y²)
=(x²-2xy+y²+x²+2xy+y²)(x²-y²)
=2(x²+y²)(x²-y²)
=2x的4次方-2y的4次方
(m-n-3)²
=(m-n)²-6(m-n)+9
=m²-2mn+n²-6m+6n+9
(x-2y+z)(-x+2y+z)
=[z+(x-2y)][z-(x-2y)]
=z²-(x-2y)²
=z²-x²+4xy-4y²
1995×1997=(1996-1)(1996+1)=1996²-1
1993×1999=(1996-3)(1996+2)=1996²-9
∴1995×1997>1993×1999