Could someone please give me a walkthrough of the following question(and answer)?? I really can't understand it.... lim x^2 = 9 x->3 if 0<|x-c|<delta then |f(x) - L|< epsilon so... x^2 - 9 = (x+3)(x-3) |x^2 - 9| = |x+3||x-3| Here's the problem.The book states: An estimate of what??And how do I know when I must estimate??I'm guessing that it doesnt matter whether (x+3) or (x-3) is chosen due to the absolute value brackets..? anyway: if |x-3|<1 then 2<x<4 (Choosing a delta....now x lies between 2 and 4.) |x+3|<=|x|+|3|= x+3<7 (this would be: c-delta<x<c+delta,correct?) **How do I know when to implement that ??**Why are they now using |x+3| instead of (x-3)?!? if |x-3|<1 then |x^2 -9|< 7|x-3| I understand that this solution basically states delta = 1/7 epsilon??And I know that the 7 is acquired through the c-delta<x<c+delta formula/method but I'm still too lost!! please clarify guys!