x²-(y-z)²/(x+y)²-z²

x²-(y-z)²/(x+y)²-z²
x²-(y-z)²/(x+y)²-z²

x²-(y-z)²/(x+y)²-z²
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)=1-2y/(x+y+z)

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

原式=【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)=1-2y/(x+y+z)请问（x+y-z)(x-y+z)/(x+y-z)(x+y+z)怎么来的，我比较笨啦，请你指明一下。谢谢了！！平方差公式 a²-b²=(a-b)(a+b) 把(y-z)...

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原式=【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)=1-2y/(x+y+z)

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