若x^?+x^-?=9,则x^2+1/x^2=?若x^?-x^-?=3,则x^2+1/x^2=?

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若x^?+x^-?=9,则x^2+1/x^2=?若x^?-x^-?=3,则x^2+1/x^2=?
我打错了，应是若x^1/2+x^-1/2=9,则x^2+1/x^2=?
若x^1/2-x^-1/2=3,则x^2+1/x^2=?

这就看你对问题的把握了,应定要仔细观察题目已知与未知的联系.本题中已知为一次,未知为二次,正好通过平方求得,
x^(1/2)+x^(-1/2)=9
x^2+1/x^2
=(x+1/x)^2-2
=[(x^(1/2)+x^(-1/2)^2-2]^2-2
=(81-2)^2-2
=6
会了第一个,第二个应该也会了吧,这是两次平方而已
x^(1/2)-x^(1/2)=3
x^2+1/x^2
=(x-1/x)^2+2
=[(x^(1/2)-x^(-1/2))^2+2]^2+2
=(3^2+2)^2+2
=121+2
=123

若x+x^2+x^3=-1 则x^2012+x^2011+x^2010+x^2009+…………+x^3+x^2+x+1= x^5+x^4 = (x^3-x)(x^2+x+1)+x^2+x 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若x等于它的倒数则(x-1)(x+2)/x-1÷x^2-9/x+3= 若x平方+x-1=0,则2x立方-3x平方-x=? 若x^?+x^-?=9,则x^2+1/x^2=?若x^?-x^-?=3,则x^2+1/x^2=? x/x平方-x+2=2x/x+1 解方程x/(x-2)=2x/(x-3)+(1-x)/(x-5x+6) 若x^3+x^2+x+1=0,求代数式1+x+x^2+x^3+x^4+x^5+...+x^2006+x^2007的值 x^4+x^3+x^2+x+1=0,x^2006+x^2005+x^2004+x^2003+x^2002 y=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10)的导数在x=1 设函数f(x)=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10),