Question

（x2-4x+4分之x2-4加x+2分之2-x）÷x-2分之x

Answer 1

原式=[(x+2)(x-2)/(x-2)²-(x-2)/(x+2)]×(x-2)/x
=[(x+2)/(x-2)-(x-2)/(x+2)]×(x-2)/x
=[(x²+4x+4-x²+4x-4)/(x-2)(x+2)]×(x-2)/x
=[8x/(x-2)(x+2)]×(x-2)/x
=8/(x+2)

Answer 2

焦距2c=4
c=2
e=c/a=√2/2
所以a=c/e=2√2
a^2=8
所以准线间距离=a^2/c-(-a^2/c)=2a^2/c=8

tan(a+b)=(tana+tanb)/(1-tanatanb)

追问

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