神马作文网已知a=1 2,求代数式1-2a a² a-1
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原式=3(4a²+4ab+b²)=3(2a+b)²=3×1²=3
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=
2a^2+a=54a^2+2a=104a^2+2a+1=11
∵a²+2a-3=0∴a²+2a=3∴3a²+6a-1=3(a²+2a)-1=3×3-1=9-1=8请点击下面的【选为满意回答】按钮,
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
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+2a+1=0则a²+2a=-12a²+4a-3=2（a²+2a）-3=2×（-1)-3=-5
(1a+1b)÷a2+2ab+b2a+b=a+bab÷(a+b)2a+b=a+bab÷（a+b）=1ab，当a=-3，b=2时，原式=1−3×2=-16．
a(a-1)-(a*a-b)=-5化简得a-b=5(a*a+b*b)/2-ab=1/2*(a-b)平方=25/2
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&
根据已知条件,得：a=2分之11/2+b+3=0b=-3-1/2=-7/2（-a²+3ab-1/2b²）-（-2a²+4ab+1/2b²）=-a²+3
a(a-1)-(a^2-b)=1=a^2-a-a^2+b=1b-a=11/2（a^2+b^2)-ab=(1/2)(a-b)^2=(1/2)*1^2=1/2
a=2,b=-1,c=-3所以（a+b+c)的平方=4
∵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^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