Question

急——————！！一道初二数学题

x²—（y—z）²
________________ [需过程~！]
(x+y)²—z²

Answer 1

[x²-(y-z)²]/[(x+y)²-z²]
=(x-y+z)(x+y-z)(/(x+y+z)(x+y-z)
=(x-y+z)/(x+y-z)

Answer 2

=（x+y-z）（x-y+z）/（x+y+z）（x+y-z）=（x-y+z）/（x+y+z）

Answer 3

分子分解为(x+y-z)(x-y+z)
分母分解为(x+y+z)(x+y-z)
结果分子分母均约掉相同因式得
(x-y+z)/(x+y+z)

Answer 4

解： （x+y-z）(x-y+z) x-y+z
原式= __________ =________________
(x+y+z)(x+y-z) x+y+z
上面是一个平方差公式，下面也是一个平方差公式。