已知a² a-1=0,求代数式a³ 2a² 2015的值

a/(a+1)=√10(a+1)/a=1/√101+1/a=1/√101/a=1/√10-1=(1-√10)/√101-1/a=1-(1-√10)/√10=(√10-1+√10)/√10=(2√10-

a²+a-1=0,a²+a=1a³+2a²+2012=a^3+a^2+a^2+2012=a(a^2+a)+a^2+2012=a+a^2+2012=1+2012=

a的平方+a-1=0a^2+a=1a的立方+2a的平方+2012=a(a^2+a+a)+2012=a(1+a)+2012=a^2+a+2012=1+2012=2013

a²-3a+1=0两边同除以aa-3+1/a=0a+1/a=3(1)两边平方a²+2+1/a²=9a²+1/a²=7(2)代数式a三次方/（a六次方+

a=(根号5)-1a+1=√5a²+2a+1=5∴a²+2a-4=0a^3+2a^2-4a+1=a(a²+2a-4)+1=a×0+1=1

a^2=a+1两边平方a^4=a^2+2a+1=(a+1)+2a+1=3a+2a^5=a*a^4=a(3a+2)=3a^2+2a=3(a+1)+2a=5a+2所以a^5-5a+2=5a+2-5a+2=

a^5-5a+3=a³﹙a²＋a-1﹚－a^4＋a³-5a+3=a³﹙a²＋a-1﹚－a²﹙a²＋a-1﹚＋2a³-a&

a^2+3a+1=0,显然a不等于0所以两边除以aa+3+1/a=0a+1/a=-3两边平方a^2+2+1/a^2=9a^2+1/a^2=7a^2/a^4+1上下同除以a^2=1/(a^2+1/a^2

3a^3+(a^2+5)(a^2-1)-5(a+1)(a-1)-6a=a^4+3a^3-a^2-6a=a^4+3a^3+a^2-2a^2-6a=a^2(a^2+3a+1)-2a^2-6a=-2a^2-

由[（a-2)/（a（a+2)-（a-1)/（a+2)²]÷（a-4)/（a+2)=[（a-2)(a+2)/a(a+2)²-a(a-1)/a(a+2)²=(a-4)/a(

已知a²+a-1=0,求代数式a⁵-5a的值由a²+a-1=0,得a₁=(-1+√5)/2=-(1-√5)/2；a₂=(-1-√5)/2=-(1

a²-a-1=0∵a≠0∴除以a得a-1-1/a=0a-1/a=1(a+1/a)²=(a-1/a)²+4=1+4=5∴a+1/a=±√5

a^2-a-1=0,∴a²-a=1∴a^3-2a+2010=a³-a²+a²-2a+2010=a(a²-a)+a²-2a+2010=a+a&

∵a²+2a-2012=0∴a²+2a+2012(a-2/a²+2a-a-1/a²+4a+4)/a-4/a+2=[(a-2)/a(a+2)-(a-1)/(a+2

a^3+3a^2+a-4=(a^3+a^2-a)+2(a^2+a-1)-2=a(a^2+a-1)-2(a^2+a-1)-2=a×0-2×0-2=-2

a^5-5a+2=a³×a²-5a+2=a³(a+1)-5a+2=a^4+a³-5a+2=(a²)²+a×a²-5a+2=(a+1

a²=a+1所以a⁴=(a²)²=(a+1)²=a²+2a+1=(a+1)+2a+1=3a+2所以原式=3a+2-3a+2=4

原式=a^1986*(1+a+a²)+a^1989*(1+a+a²)+...+a^2004*(1+a+a²)=a^1986*0+a^1989*0+...+a^2004*0

a^4=(a+1)^2=a^2+2a+1=3a+2a^8=(3a+2)^2=9a^2+12a+4=21a+13a^8+7a^-4=21a+13+7/(3a+2)=(63a^2+81a+26+7)/(3

[(a-2)/(a^2+2a)-(a-1)/(a^2+4a+4)]÷(a-4)/(a+2)=[(a-2)/a(a+2)-(a-1)/(a+2)^2]x(a+2)/(a-4)=[(a-2)(a+2)/a