x平方-4分之x（x-2）乘x 2分之x方 4x 4
=x(x-2)/(x²-4)×(x²-4x+4)/(x-2)
=x(x-2)/(x+2)(x-2)×(x-2)²/(x-2)
=x(x-2)/(x+2)
=(2-√2)(-√2)/(4-√2)
=(2-2√2)/(4-√2)
=(2-2√2)(4-√2)/14;
=(12-10√2)/14
=(6-5√2)/7;
如果本题有什么不明白可以追问,