ap calculus - limits, adlfjadsf Options

[*stephinika*]

yeah i've redone this question a few times and i bet its some stupid mistake but its driving me nuts...
anyone that can help?

find the limit of:
lim (as x approaches 4) (1/rootx - 1/2)/x-4

i keep on getting either a 0 in the numerator or denominator and its driving me crazy.
the first thing i did was simplify the numerator to (2-rootx)/2rootx then multiplied by the conjugate of 2+rootx leaving me with (4-x)/(4rootx+2x).
then i multiplied the conjugate again of 4root-2x and after some simplification i ended up with [(4rootx-2x)/4x]/x-4
i then multipied by the reciprocal to do the division but i ended up with {4rootx-2x)/4x(x-4)

now what?
(did that make any sense?)

edit.//
i need more help...haha

i'm so stuck, my brain isn't working. here:

find the limit:
lim (as x approaches 2) of (root(6-x) - 2)/(root(3-x)-1)

help?

and theres two more...trig limits.

lim (as x approaches 0) of (2sinx - sin2x)/xcosx

AND

lim (as x approaches 0) of (sinx)/(x + sinx)


ugh. my brain is hurting. this is what happens when you procrastinate and forget all you learned in class almost a weekago....

This post has been edited by stephinika: Oct 10 2005, 09:51 PM

[silver-rain]

Hmm, ok yay limits.
OK, I don't think you need to do the second conjugate. Instead, you could change the 4-x to -(x-4) and the (x-4) cancels out. Then, you get -1/4rootx + 2x. You just substitute the 4 for x and should get -1/16.