已知a=√2 -1,化简求值(a^2-1/a-1)-(√a^2-2a+1 /a^2-a)-1/a
已知a=√2 -1,化简求值(a^2-1/a-1)-(√a^2-2a+1 /a^2-a)-1/a
(a^2-1/a-1)-(√a^2-2a+1 /a^2-a)-1/a
=(a+1)(a-1)/(a-1)-√(a-1)^2/[a(a-1)]-1/a
=(a+1)-|a-1|/[a(a-1)]-1/a
∵a=√2-1
∴a-1=√2-2<0
∴原式
=(a+1)-(1-a)/[a(a-1)]-1/a
=a+1+1/a-1/a
=a+1
=√2-1+1
=√2
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化简求值(a-1)/(a-2)乘(a^2-4)/(a^2-2a+1)除1/(a^2-a),其中a满足a^2-a=0
(a-1)/(a-2)乘(a^2-4)/(a^2-2a+1)除1/(a^2-a)
=(a^2-a)*[(a-1)/(a-2)乘(a^2-4)/(a^2-2a+1)]
=0*[(a-1)/(a-2)乘(a^2-4)/(a^2-2a+1)]
=0
化简求值:已知1+1/a=3.求[(a^2-5/a-1)+1]×(a^2-1/a^2-2a)÷(a+3)=
解: 1+1/a=3, a=1/2 将a=1/2代入式子得: [((1/2)^2-5/(1/2-1))+1]×((1/2)^2-1/(1/2)^2-2*(1/2))÷(1/2+3) = [1/4-10]*(1/4-8)÷7/2 =39/31*2/7 =78/217
化简求值(a-1/a+2)×(a^2-4/a^2-2a+1)÷(1/a^2-1),其中a满足a^2-a=1
解:(a-1)/(a+1)×(a-2)(a+2)/(a-1)² ×(a-1)(a+1)
=a²-4
化简求值(a-1/a+2)×(a^2-4/a^2-2a+1)÷(1/a^2-1),其中a满足a^2-a=0
原式=(a-1/a+2)×[(a-2)(a+2)/(a-1)^2]×(a-1)(a+1)
因为a^2-a=0 即a(a-1)=0 所以a=0 或1
当a=1时,作为分母的a^2-2a+1=(a-1)^2=0 不成立,所以a=0
继续化简原式=(a-2)(a+1)
将a=0带入 原式=-2
化简求值:{2+[1/(a-1)]-[1/(a+1)]}÷{a-[a/(1-a^2)]},a=2
{2+[1/(a-1)]-[1/(a+1)]}÷{a-[a/(1-a^2)]}
={2+1/(a-1]-1/(a+1])÷{(a-a^3)/(1-a^2)-a/(1-a^2)]
={2+[(a+1)/(a^2-1)÷[-a^3/(1-a^2)
=(2+2/(a^2-1))÷[-a^3/(1-a^2)
=(2+2/(a^2-1))*[(a^2-1)/a^3
=2(a^2-1)/a^3+2/a^3
=(-2+2a^2+2)/a^3
=2a^2/a^3
=2/a
,a=2
=-2/2
=1
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已知a=1/(2+√3) 化简求值(√a)+√((1/a^2)+a^2-2)
a=1/(2+√3) =2-√3>0,1/a-a>0
1/a=2+√3,1/a-a>0
(√a)^2+√((1/a^2)+a^2-2)
=(√a)^2+√(1/a-a)^2
=a+1/a-a
=1/a
=2+√3
化简 [a^2-1]/[a-1]-√[a^2-2a+1]/a^2-a]
a=1/[2+√3]=(2-√3)/(2+√3)(2-√3)=2-√3
1/a=2+√3
a-1<0
于是
原式
=(a+1)(a-1)/(a-1)-√(a-1)²/[a(a-1)]
=(a+1)+(a-1)/[a(a-1)]
=a+1+1/a
=2-√3+1+(2+√3)
=3-√3+2+√3
=5
化简求值(1-(1/a-1))除以a^2-4a+4/a^2-a其中a=-1
[1-1/(a-1)]÷[(a²-4a+4)/(a²-a)]
=(a-2)/(a-1)÷[(a-2)²/a(a-1)]
=(a-2)/(a-1)*[a(a-1)/(a-2)²]
=a/(a-2)
当a=-1时,原式=-1/(-1-2)=1/3
化简:(a^2-a)÷(a^2-2a+1)/(a-1)
(a^2-a)÷(a^2-2a+1)/(a-1)
=a(a-1)÷(a-1)^2/(a-1)
=a(a-1)÷(a-1)
=a
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