x+1\x=根号11,求x-1\x的值。(x>x分之一,误差小于0.1)
x+1\x=根号11,求x-1\x的值。(x>x分之一,误差小于0.1)
(x+1/x)^ 2=11
X^ 2+1/(X^ 2)+2=11
X^ 2+1/(X^ 2)=11-2=9
(X-1/X)^ 2=X^ 2+1/(X^ 2)-2=9-2=7
因为X大于1/X,
所以:x-1/x=√7
x+1\x=根号11
那么(x+1\x)^2=11 x^2+1/x^2+2=11 x^2+1/x^2=9
(x-1\x)^2=x^2+1/x^2-2=9-2=7 所以x-1\x=根号7=2.646 (x>x分之一所以为正)