# Search results

1. ### D/dx of ln(|x|)

Thank You ! Everyone for your valuable suggestions .
2. ### D/dx of ln(|x|)

I know d/dx of ln(x) is 1/x , x>0. A website says d/dx of ln(|x|) is also 1/x for x not = 0 . is that true , i am unable to prove it!
3. ### Second derivative from parametric form

If x and y are defined in terms of a third vatiable say t , then to find d2y/dx2 , we cannot find d2y/dt2 and d2x/dt2 and divide them to get d2y/dx2 , i am unable to fingure out the reason for this !!!!!!!
4. ### A strange solution ?

a strange solution ?????? I was solving a tangent problem and came accross a strange thing , its a simple quadratic equation ,y2 - 4y -8 = 0 , by quadratic formula , y = 2 + 2*31/2 and 2 - 2*31/2 , now if i write the same quadratic as (y-2)2 = 12 , then i apply square root function on...
5. ### 2 different dy/dx of xy=c^2

I have a relation xy=c2 , if i apply implicit differentiation to both sides i get dy/dx =-y/x , but if i write the same thing as y=c2/x , then dy/dx comes out to be -c2/x2 , whats going wrong ??????
6. ### Second derivative test for x^3

Does the second derivative test fail for x3 at x=0: f'(x)=3x2 f''(x)=6x , for x=0, f'(0)=0 & f''(0)=+ve , so it should be a point of local maxima , but it is not!!!!!!!!!!
7. ### Modulus limit complication

lim as h->0 (|(h^2) + 4h |)/h comes out = 4 when i do it by splitting the definition of function according to modulus , but if according to distributive property of modulus , i can also write it as lim as h->0 (|h|/h)|((h) + 4|)) , but im as h->0 (|h|/h) does not exist , so whats wrong????????
8. ### Extreme Value Theorm

Thanx man!!!!!!!!!!!! i got it.
9. ### Extreme Value Theorm

How is Extreme Value Theorm correct for a constant function such as y=1 , where is the maximum and minimum????????
10. ### Emf continued

This is in continuation to https://www.physicsforums.com/showthread.php?t=330495 The question that initiated my doubt reads this -- " the internal resistance of an accumulator battery of emf 6V is 10 Ohm when fully discharged . as battery gets charged up , its internal resistance drops to 1...
11. ### EMF and charging of a battery

now i am a bit confused , even i think that the emf changes , but i am unable to figure out the reason , could someone just explane it . pls....
12. ### EMF and charging of a battery

so this means that the emf does not change , the extra potential applied just gets converted to chemical energy , did i get it right ??
13. ### EMF and charging of a battery

My doubt is that when we charge a battery we say that energy is transferred into it , but does the emf of a battery change in this process ? Is the emf same before and after charging , if yes then what actually happens during charging a battery ?? pls help !!!!!!!!!!!