2倍根号3加2分之根号5减10倍的根号0点004
=2√3+√5/2-10√0.004
=2√3+√5/2-10√(1/5²×10)
=2√3+√5/2-10*√10/50
=2√3+√5/2-√10/5保留两位小数，写的简练点，谢谢=2√3+√5/2-√10/5≈2*1.732+2.236/2+3.162/5=5.214≈5.21