注:我用sqrt( x )表示x开平方因为sqrt(19.99) = 4.471,所以sqrt( 0.001999 ) = sqrt( 0.0001*19.99 ) = sqrt( 0.0001 ) * sqrt( 19.99 ) = 0.01 * 4.471 = 0.04471,同理可得sqrt( 1999 ) = 44.71,所以所求 = 44.71 +...