当a=1/√3+√2,b=1/√3-√2时,求代数式a√a+b√b/√a+√b-1/√(a-1)²+1/√(b-1)²的值

问题描述:

当a=1/√3+√2,b=1/√3-√2时,求代数式a√a+b√b/√a+√b-1/√(a-1)²+1/√(b-1)²的值

a=1/√3+√2=√3-√2
b=1/√3-√2=√3+√2
∴a+b=2√3,a-b=-2√2,ab=1
a√a+b√b/√a+√b-1/√(a-1)²+1/√(b-1)²
=[(√a)³+(√b)³] /(√a+√b) -[1/(a-1)²-1/(b-1)²]
=[(√a+√b)(a+b-√ab)] /(√a+√b) -[1/(a-1)+1/(b-1)][1/(a-1)-1/(b-1)]
=(a+b-√ab)-[(b-1+a-1)/(a-1)(b-1)][(b-1-a+1)/(a-1)(b-1)]
=(a+b-√ab)-[(a+b-2)(b-a)/(a-1)²(b-1)²]
=(a+b-√ab)+(a+b+2)(a-b)/(ab-a-b+1)²
将a+b=2√3,a-b=-2√2,ab=1代入:
原式=(2√3-1)+(2√3+2)(-2√2)/(1-2√3+1)²
=(2√3-1)-2√2(2√3+2)/(2-2√3)
=(2√3-1)+2√2(√3+1)/(√3-1)
=(2√3-1)+√2(√3+1)²
=2√6+2√3+4√2-1