设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于A根号6 B根号2 C-2 D2若m^3/2+m^-1/2=4,则(m^3/2-m^-3/2)/(m^1/2-m^-1/2)=?化简 (a^1/2-b^1/2)/(a^1/2+b^1/2)+(a^1/2+b^1/2)/(a^1/2-b^1/2)=?
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![设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于A根号6 B根号2 C-2 D2若m^3/2+m^-1/2=4,则(m^3/2-m^-3/2)/(m^1/2-m^-1/2)=?化简 (a^1/2-b^1/2)/(a^1/2+b^1/2)+(a^1/2+b^1/2)/(a^1/2-b^1/2)=?](/uploads/image/z/2742313-49-3.jpg?t=%E8%AE%BEx%3E1%2Cy%3E0%2C%E8%8B%A5x%5Ey%2Bx%5E-y%3D2%E6%A0%B9%E5%8F%B72%2C%E5%88%99x%5Ey-x%5E-y%E7%AD%89%E4%BA%8EA%E6%A0%B9%E5%8F%B76+B%E6%A0%B9%E5%8F%B72+C-2+D2%E8%8B%A5m%5E3%2F2%2Bm%5E-1%2F2%3D4%2C%E5%88%99%28m%5E3%2F2-m%5E-3%2F2%29%2F%28m%5E1%2F2-m%5E-1%2F2%29%3D%3F%E5%8C%96%E7%AE%80+%28a%5E1%2F2-b%5E1%2F2%29%2F%28a%5E1%2F2%2Bb%5E1%2F2%29%2B%28a%5E1%2F2%2Bb%5E1%2F2%29%2F%28a%5E1%2F2-b%5E1%2F2%29%3D%3F)
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于A根号6 B根号2 C-2 D2若m^3/2+m^-1/2=4,则(m^3/2-m^-3/2)/(m^1/2-m^-1/2)=?化简 (a^1/2-b^1/2)/(a^1/2+b^1/2)+(a^1/2+b^1/2)/(a^1/2-b^1/2)=?
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于
A根号6 B根号2 C-2 D2
若m^3/2+m^-1/2=4,则(m^3/2-m^-3/2)/(m^1/2-m^-1/2)=?
化简 (a^1/2-b^1/2)/(a^1/2+b^1/2)+(a^1/2+b^1/2)/(a^1/2-b^1/2)=?
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于A根号6 B根号2 C-2 D2若m^3/2+m^-1/2=4,则(m^3/2-m^-3/2)/(m^1/2-m^-1/2)=?化简 (a^1/2-b^1/2)/(a^1/2+b^1/2)+(a^1/2+b^1/2)/(a^1/2-b^1/2)=?
D
x^y+x^-y=2根号2===>(x^y+x^-y)^2=8===>x^2y+x^-2y+2=8===>x^2y+x^-2y=6
(x^y-x^-y)^2=x^2y+x^-2y-2=6-2=4==>x^y-x^-y=2
(a^1/2-b^1/2)/(a^1/2+b^1/2)+(a^1/2+b^1/2)/(a^1/2-b^1/2)=[(a^1/2-b^1/2)^2+(a^1/2+b^1/2)^2]/(a^1/2-b^1/2)(a^1/2+b^1/2)=2(a+b)/(a-b)