有三道二次根式的题,速解,第一道是化简题,后两道是计算题

(5√2+2√3)/(5+√6)+(3-√3)/(√3-1)-(4-2√2)/(√2-1)
=√2(5+√6)/(5+√6)+√3(√3-1)/(√3-1)-2√2(√2-1)/ (√2-1)
=√2+√3-2√2
=√3-√2
=((1+√(1-x²))/√(1+x))/(1+√(1-x²)
=1/√(1+x)
=√(1+x) /(1+x)
=√((x²-y²)((x²)²-(y²)²))=√((x²-y²)(x²-y²) (x²+y²))
=√((x²-y²)²(x²+y²))
=(x²-y²)√( (x²+y²))

√[(x^2-y^2)(x^4-y^4)]=√[(x^2-y^2)^2(x^2＋y^2)]=(x2^-y^2)√(x^2＋y^2)。