7*7=49
7.05*7.05=49.705
7.06^2=49.8436
7.07^2=49.9849
7.08*7.08=50.1264
7.075*7.075=50.055625
7.072*7.072=50.013184
7.071*7.071=49.99041
所以50的平方根约等于7.071