Posted by Ruby on Friday, October 26, 2012 at 11:28am.
y = x^(1/2)
dy/dx = (1/2)x^(-1/2)
dy = 1/(2√x) dx
when x = 64, dx = .3
dy = (1/2√64)(.3) = (1/16)(.3) = appr .01875
so √64.3 = 8.01875
actual √64.3 by calculator = 8.018729
error is .000022