a )Expand (x+x^-1)^2 =(x+a/x)^2 =x^2+2+1/x^2 b.(x+x^-1)^2=x^2+2+x^-2 25=x^2+2+x^-2 x^2+x^-2=23
Mr-Brian
2006-10-26 22:37
引用第22樓SuN FoReVeR於2006-10-26 22:34發表的“”: a )Expand (x+x^-1)^2 b )given that x + x^-1 = 5 ,determine x^2 + x^-2 A) =x^2+2(x)(x^-1)+x^-2 =x^2+(x^-2)+2 b)x+x^-1=5 TAKE SQUARE BOTH SIDE x^2+(x^-2)+2=25 x^2+(x^-2)=25-2=23 .......