4道初二上学期因式分解题目(1) -4-4xy-x²y²(2) 1/2x²+2xy+2y²(3) 4(x+y)²-25(4) 4a²-(a²+1)²
问题描述:
4道初二上学期因式分解题目
(1) -4-4xy-x²y²
(2) 1/2x²+2xy+2y²
(3) 4(x+y)²-25
(4) 4a²-(a²+1)²
答
(1) -4-4xy-x²y²
=-(x²y²+4xy+4)
=-(xy+2)²
(2) 1/2x²+2xy+2y²
=1/2(x²+4xy+4y²)
=1/2(x+2y)²
(3) 4(x+y)²-25
=(2x+2y)²-5²
=(2x+2y+5)(2x+2y-5)
(4) 4a²-(a²+1)²
=[2a+(a²+1)][2a-(a²+1)]
=(a+1)²[-(a²-2a+1)]
=-(a+1)²(a-1)²