Prove that , if x is so small that terms in x^3 and higher powers may be neglected, then Attachment 21081.

By substituting a suitable value of x in your result, show that (11)^1/2 is approximately equal to 663/200.

I can solve the first part, but i have difficulty in the second part (show that (11)^1/2 is approximately equal to 663/200). Can anyone help me? Thanks.