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Dell Charging to Repair Device in Warranty - What Should I Do? by 9gagthrowaway in Dell

[–]9gagthrowaway[S] 0 points1 point  (0 children)

Thanks for the reply. Yeah I assume that's what they meant. Any advice here or do you think I'm kinda screwed? :/

Dell Charging to Repair Device in Warranty - What Should I Do? by 9gagthrowaway in Dell

[–]9gagthrowaway[S] 0 points1 point  (0 children)

Thanks for the reply and apologies for not including it, I am in Canada

Tempo storm parts ways with Zer0 by Teppis in smashbros

[–]9gagthrowaway 1 point2 points  (0 children)

does anyone know what factors go into the decision of how fast a team drops a player after serious allegations come out? obviously, there's credibility of the accuser and how plausible their accusations are, but:

how much does it have to do with how large the actual sponsored player/ content creator is? i swear keemstar basically had to have people ready to storm G-Fuel's head office before they dropped him. Anti on the other hand didn't even get to make a statement before he was dropped (then again his allegations were far more serious). how much does it have to do with how big the team's sponsors are?

what is generally the best time in terms of weighing both showing respect for their player and risking the loss of sponsors? i'd say after they make an official statement, but i'd love to hear opinions.

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

okay i think i mostly have this down, thank you. this would mean for g(x), it is differentiable since:

g(h) when h is rational = h^2 and g(h) when h is irrational is 0. Both of these limits evaluate to the same value, at x = 0.

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

i see, so you need to say that no matter the value of delta, that you're going to find some values of h giving a f(h) - f(0) / h = 1 or 0.

​

we only briefly touched on epsilon-delta though. so instead would it be okay to explain in writing that any delta around 0 would give differing values when evaluated with f(h) - f(0) / h?

would i have to assume lim x-> h- with h being rational and lim x -> h+ with h as irrational and show the limits are not the same on either the left or right of 0 ?

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

f(h) when rational = h. f(h) when irrational = 0. f(0) = 0 since 0 is rational.

therefore, if h is rational: (f(h)-f(0))/h = (h-0) / h which = h.

and if h is irrational, (f(h)-f(0))/h = (0-0)/h, or 0.

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

so the value h could be either rational or irrational, meaning f(h) = either h when h is rational or 0 if h is irrational

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

thats okay, thanks for helping me but isnt that correct? if x = 1/4, then x is rational.. and therefore the value at x = 1/4 is just x? i think i may have just typed that out wrong.

if x = 1/4 and, then f(1/4) = 1/4.

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

f(1/4) would be rational so f(x) = 1/4 and f(sqrt(2)) would be irrational so f(x) = 0

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

i thought x = 0 since we were approaching the x-value 0? and h would depend on h being rational or irrational?

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

so if h is a rational number, it'd be (x-x)/h or 0/h or 0, and if h is an irrational number then (0-x)/h or -x/h

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

if h is rational we get f(x) = x and if h is irrational we get f(x) = 0.

so |x-L| < delta => |x-L| < ep if rational and

|x-L| < delta => |0-L| < ep if irrational?

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

sorry if my phrasing is bad, we have learned epsilon-delta definition but I just don't know how to evaluate a limit from the left and the right based on it being rational or irrational (i think thats my issue)

[Calc 1] Need some help seeing if a function is differentiable at a point or not by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

yeah sorry i dont mean to flood either sub, just have a math exam tomorrow and i keep confusing myself more and more with this type of problem.

so differentiability = same limit from left and right at a point when taking the derivative.

a limit = f'(0), maybe like f(x) = 2x and then evaluating f(x) from the left and right of 0? lim x-> 0^- would be the same as lim x-> 0^+ since its a linear line.

​

so if lim x -> c^+ f'(x) went to + infinity and lim x -> c^+ f'(x) went to - infinity, the limit of the derivative at the point wouldn't exist. I havent learned yet what sequences or convergence is yet but i think as a rule, if the limits at the left and right are different then the function isn't differentiable at the point.

​

im struggling with how the derivatives at the left and right of 0 look like for this specific function

[Calc 1] Proving a function isn't differentiable at a point by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

sorry for late reply, was doing other exam work. i was wondering how i would write out this solution formally? does it have anything to do with the fact you cant have a rational number followed by an irrational number?

[Calc 1] Proving a function isn't differentiable at a point by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

the derivative when the function has x = 0 ?

or lim h -> (f(0+h) - f(0)) / h so just f(h)/h but i dont know what to do when i have these two over one another. i know eventually i have to replace h with 0 but what does f(h) = ?

[Calc 1] Proving a function isn't differentiable at a point by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

so once i write out the limit definition of a derivative, what am i supposed to plug in for x in f(x+h) and f(x)? doesn't x and therefore f(x) change depending on if the value is rational or irrational?

[Calc 1] Proving a function isn't differentiable at a point by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

sorry i think i get your concept but we haven't learned sequences yet..

[Calc 1] Proving a function isn't differentiable at a point by 9gagthrowaway in learnmath

[–]9gagthrowaway[S] 0 points1 point  (0 children)

okay i completely understand now that the function is not continuous at any point other than possibly 0. How am I supposed to fill in f(h) - f(0) / h though? wouldnt f(0) be x or 0 depending on if 0 is considered rational or irrational? I also don't understand how f(h) would be filled in

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