a的平方减a加1等于7-搜答案-搜搜考试网

a的平方减4a加1等于0a-4+1/a=0a+1/a=4

a^2+3a+1=0a^2+1=-3a都除以a可得a+1/a=-3a^2+1/a^2=(a+1/a)^2-2=9-2=7a^2-2+1/a^2=7-2=5所以a-1/a=√5

(A²B²-2AB+1)+(A²+B²-2AB)=0(AB-1)²+(A-B)²=0AB=1A=B∴A和B同时等于1或-1∴A+B=2或-2

因为　a^2--3a+1=0所以　a--3+1/a=0a+1/a=3a^2+2+1/a^2=9a^2+1/a^2=7所以　(a^4+a^2+1)/a^2=a^2+1+1/a^2=a^2+1/a^2+1

a^2-3a+1=0a^2+1=3aa+1/a=3a^2+1/a^2=a^2+2+1/a^2-2=(a+1/a)^2-2=3^2-2=7

=[√(a^2-1)+√(1-a^2)]/(a+7)+4√(a^2-1)>=0a^2>=1a>=-1或a=0-1

√(a^2-2a+1)=0√(a-1)^2=0(a-1)^2=0a=1

a^2+a-1=5,a^2+a-1-5=0,a^2+a-6=0,(a-2)(a+3)=0,a=2或a=-34a^3+4a^2-7=4a(a^2+a-1)+4a-7=20a+4a-7=24a-7a=2时

a^2-√10a+1=0a^2+1=√10a两边除aa+1/a=√10两边平方a^2+2*a*1/a+1/a^2=10a^2+2+1/a^2=10a^2+1/a^2=8

a^2+a+1/4=a^2+(2*1/2*a)+(1/2)^2=(a+1/2)^2【学习宝典】

=(a-b+1)²=[(a-b)+1]²=(a-b)²+2(a-b)+1=a²-2ab+b²+2a-2b+1再问：确定吗？再答：是的啊

(ab)^2+a^2+b^2+1-2ab=2ab(ab)^2+(a-b)^2+1-2ab=0ab(ab-2)+(a-b)^2+1=0a=-1,b=-1a+b=-2

解(a²+b²)×(a²+b²-1)=6令a²+b²=t则t(t-1)=6即t²-t-6=0(t-3)(t+2)=0∴t=3或t=

∵a²-a-1=0∴a²=a+1∴a²+1/a²=(a+1)+1/(a+1)=(a²+2a+2)/(a+1)=(a+1+2a+2)/(a+1)=3

a²+a=1a²+a-1=0a=（-1+√5）/2或（-1-√5）/2

再问：再答：

a^2+ab=4ab+b^2=-1所以a^2-b^2=(a^2+ab)-(ab+b^2)=4-(-1)=5

a²+5a-1=0a+5-1/a=0∴a-1/a=-5两边平分得a²-2+1/a²=25∴a²+1/a²=27