Question

求数学学霸，急

Answer 1

1/(√3+√2)-2/(√3-1)
=(√3-√2)/[(√3+√2)(√3-√2)]-2(√3+1)/[(√3-1)(√3+1)]
=√3-√2-√3-1
=-√2-1

(√a-√b)÷(√a+√b)
=[(√a-√b)(√a-√b)]/[√a+√b)(√a-√b)]
=(√a-√b)²/(a-b)
=(a+b-2√ab)/(a-b)

(3√m+2√n)÷(2√m-√n)
=[3√m+2√n)(2√m+√n)]÷[2√m-√n)(2√m+√n)]
=(6m+7√mn+2n)/(2m-n)

(√x/y-√y/x)÷(1/√y-1/√x)
=(1/y√xy-1/x√xy)÷(√y/y-√x/x)
=√xy(1/y-1/x)÷[(x√y-y√x)/xy]
=√xy[(x-y)/xy)÷[(x√y-y√x)/xy]
=√xy(x-y)÷(x√y-y√x)
=[√xy(x-y)(x√y+y√x)]÷[(x√y-y√x)(x√y+y√x)]
=[(x-y)(x√xy²+y√x²y)]÷(x²y-xy²)
=[(x-y)(xy√x+xy√y)]÷[xy(x-y)]
=√x+√y

Answer 2

第二题：=1 - （2倍根号下ab）除以（a-b）

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