Very simple derivative

  • Thread starter yoleven
  • Start date
  • #1
78
0

Homework Statement


3/x^2

when I take the quotient rule ,
I get:
(0*x^2-3*2x)/(x^2)^2
isn't that -6x/x^4 or -6/x^3
My calculator says -6 and so it is, but why and what am I missing?
 

Answers and Replies

  • #2
73
0
ok From what i see you are right.the answer is -6x^-3.

but at what point are you evalusting.did they give you a point or did you just type on your calculator.you have to have value of x.to type on your calculator
 
  • #3
78
0
I originally had to differentiate f(t)=cos^-1(3/t^2)
my answer was f'(t)=-1/sqrt(1-(3/t^2)^2)*-6t
f'(t)=6t/sqrt(1-9/t^4)
I got the "-6t" part wrong, it was supposed to be just -6.

when I differentiate just 3/x^2 into my calculator and it comes out -6
on my ti89 calc. I go to math, calculus, differentiate and type in:
d(3/x^2,x) and get -6
 
  • #4
70
0
Instead of using the quotient rule, you might find it easier to evaluate
3 x^-2
 
  • #5
78
0
Oky, thanks. I see my problem.
I should have looked into the mirror sooner, the problem was there all along!
 

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