先化简,再求值(a-3分之1 1)除以2a-6分之a的平方-4

(a-3分之1-a²-1分之a+1)×(a-3)=(a-3)/(a-3)-(a+1)(a-3)/(a+1)(a-1)=1-(a-3)/(a-1)=(a-1-a+3)/(a-1)=2/(a-1

根号下a平方+a平方分之1-2减a分之1=√(a-1/a)²-1/a=|a-1/a|-1/a=1/a-a-1/a=-a=-3分之2

（1）原式=（a-1/2+a+1/2)(a-1/2-a-1/2)(a+3)=-2a(a+3)=-2×(-2)(-2+3)=4(平方差公式)（2）原式=（x-1/2y-1)³=（1.5-0.4

（a-1/a）=(a²-1)/a=.(a+1)(a-1)/a÷a分之a方+2a+1=÷(a²+2a+1)a=÷(a+1)(a+1)/a=*a/[(a+1)(a+1)]（a-a分之1

原式=[1-1/(a+1)]-[a/(a²+2a+1)]=1-1/(a+1)-a/(a+1)²=(a+1)²/(a+1)²-(a+1)/(a+1)²-

=[(a²-4)/(a-2)]×1/a(a+2)=[(a+2)(a-2)/(a-2)]×1/a(a+2)=(a+2)×1/a(a+2)=1/a

.(a-1分之3a剪a+1分之a)乘以a分之a²剪1=[3a/(a-1)-a/(a+1)]×(a+1)(a-1)/a=3a/(a-1)×(a+1)(a-1)/a-a/(a+1)×(a+1)(

=(a-3)/2(a-2)÷[5/(a-2)-(a+2)(a-2)/(a-2)]=(a-3)/2(a-2)÷(5-a²+4)/(a-2)=(a-3)/2(a-2)×[-(a-2)/(a+3)

∵|a+3b+1|≥0，（2a-4）2≥0，且|a+3b+1|+（2a-4）2=0，∴2a-4=0且a+3b+1=0，∴a=2，b=-1（3分），∵原式=3a2b-（2ab2-2ab+3a2b）+2a

(4分之3a的4次方b的7次方+2分之1a的立方b的8次方-9分之1a的平方b的6次方）÷（-3分之1ab的立方）的平方=(3/4a^4b^7+1/2a^3b^8-1/9a^2b^6)÷(1/9a^2

2a-4分之3-a/(a+2-a-2分之5),=(3-a)/2(a-2)÷[(a+2)(a-2)-5]/(a-2)=(3-a)/2÷(a²-9)=（3-a）/2÷[（a+3）（a-3）]=-

a-a/3+1-a+a/2-3/a²-a²/4-6a+9=-35a/6-3/a²-a²/4+10a取6,得-35-1/12-9+10=-34又1/12

（a+2a+1）/（a-1）-a/(a-1)=(a+1)^2/(a+1)(a-1)-a/(a-1)=(a+1)/(a-1)-a/(a-1)=1/(a-1)由a=根号3+1,所以原式=1/(a-1)=1

原式=(3+a)(3-a)/(a+3)^2x(a+3)/(a-3)a-1/a=-1/a-1/a=-2/a=-2/根号2=-根号2

答：a=1/(2+√3)=(2-√3)/[(2+√3)(2-√3)]=(2-√3)/(4-3)=2-√3所以：0

a/(a-3)-(a+6)/(a²-3a)+3/a=(a²-a-6+3a-9)/a(a-3)=(a²+2a-15)/a(a-3)=(a-3)(a+5)/a(a-3)=(a

；(A+2)²-(1-A)（-A-1）=A²+4A+4-(A²-1)=4A+5=4×3／2+5=11

化简：原式化简通分利用平方差公式(a+2b)/(a+b)+2b^2/(a^2-b^2)=(a+2b)(a-b)/(a+b)(a-b)+2b^2/(a^2-b^2)=(a^2+ab-2b^2)/(a^2

(a-2)分之a-(a²-2a)分之2a-a分之2=[a(a-2)]分之a²-[a(a-2)]分之(2a)-[a(a-2)]分之[2(a-2)]=[a(a-2)]分之[a²