Geomtrical Application of Differentiation HELP!! (1 Viewer)

[RHINO7]

Please help me, I'm having trouble with this question-

Show that f(x)= 1/x3 has no stationary points. That is x to the power of 3.

 

[Forbidden.]

You don't need working out to explain.

Anything divided by zero is undefined.

Now to find a stationary point of something the function must equal zero.

Now place any non-zero value in 1/x³and you will always get a non-zero answer, always.

The only way to attempt to get zero from 1/x³ is by placing 0 in the denominator. But dividing by zero is not allowed. So there is NO stationary points.


Mathematically I'd write:

f(x) = 1/x³

dy/dx = 0

1/x³ = 0

But x cannot be equal to zero.

.: 1/x³ has no stationary points.

 

[watatank]

f (x) = x^(-3)

f ' (x) = -3 (x^[-4])

Stat point is where f'(x)= 0

-3 (x^[-4]) = 0

Someone else can give proper reasoning but basically you cant solve for x in that equation and that's why there is no stationary point..

 

[Forbidden.]

Holy Shit I Forgot To Derive !!!

Omfg F**k U Integrations Trapezoidal Rule Coz U Dont Need To Integrate Yet.

 

[pc4pc]

f (x) = x^(-3)

f ' (x) = -3 (x^[-4])

Stat point is where f'(x)= 0

-3 (x^[-4]) = 0

Someone else can give proper reasoning but basically you cant solve for x in that equation and that's why there is no stationary point..

correct. that is assuming rhino7 uses maths in focus, the answer then becomes -3/x^4.

 

[watatank]

^^ it doesnt matter how the answer is supposed to be set out, the point is that it doesnt have a stationary point

Holy Shit I Forgot To Derive !!!

Omfg F**k U Integrations Trapezoidal Rule Coz U Dont Need To Integrate Yet.

Take it easy integration is like the easiest topic of all the year 12 content you will learn

 

[pc4pc]

i know. just incase OP doesn't understand why your answer doesn't match the textbook answer =]