来自李凤仁的问题
(1)x²-4xy+4y²-10x+20y+25(2)(n+1)(n+2)(n+3)(n+4)+1第一题都是二次方
(1)x²-4xy+4y²-10x+20y+25
(2)(n+1)(n+2)(n+3)(n+4)+1
第一题都是二次方
1回答
2019-08-23 06:45
(1)x²-4xy+4y²-10x+20y+25(2)(n+1)(n+2)(n+3)(n+4)+1第一题都是二次方
(1)x²-4xy+4y²-10x+20y+25
(2)(n+1)(n+2)(n+3)(n+4)+1
第一题都是二次方
(1)x²-4xy+4y²-10x+20y+25=x²-2×2xy+(2y)²-(10x-20y)+25=(x-2y)²-2×5(x-2y)+5²=(x-2y-5)²(2)(n+1)(n+2)(n+3)(n+4)+1=(n+1)(n+4)(n+2)(n+3)+1=(n²+5n+4)(n²+...