I have a few problems that i don't understand the answer..
answer is cu(-infinity, +infinity)...how do you determine that it is up? and why is it -infinity, infinity...
f'(x)= 4/7 x^-3/7
answer is cd(-infinity,0) U (0, infinity).....how do u plug numbers into f"(x) to determine which direction its concave... if i plug in f(-1) would it not be -12/49 (-1)^-10/7..but it would be positive...so how do they get (-)
f(x)= root 4-x = (4-x)^1/2
amswer s cd (-infinity,4)......if i plug in say f(5) i'd get a positive..so why is it not cd(-infinity,4) AND cu (4, infinity)?
thanks a bunch...i really appreciate u guys helping me, i only have bits and pieces of this stuff..but i'm getting the bigger picture a little at a time