Qualification > Math

Need help!!! how to solve tis!!!

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guowie88:
thk u very much !!! ^^ appreciate it *thumbs up* for u  XD

Deadly_king:

--- Quote from: ashish on October 21, 2010, 06:36:45 am ---thanks again but i am stuck on the second part , i think i didn't quite understand the question ! can you help how can normal have maximum value?

--- End quote ---

The graph represents a curve and as you move along the curve gradient of the tangent changes. This will cause gradient of normals to change as well. The question stated that the gradient of the normal has its maximum value at P which implies the d/dx(gradient of normal) = 0.

The result you obtained in the first part is actually the gradient of the normal in terms of x.

Maximum value ---> stationary value ----> d/dx = 0

Hence you need to differentiate your answer to part 1 and equate it to zero to obtain the required solution ;)

Hope it helps :)

ashish:

--- Quote from: Deadly_king on October 21, 2010, 06:53:29 am ---The graph represents a curve and as you move along the curve gradient of the tangent changes. This will cause gradient of normals to change as well. The question stated that the gradient of the normal has its maximum value at P which implies the d/dx(gradient of normal) = 0.

The result you obtained in the first part is actually the gradient of the normal in terms of x.

Maximum value ---> stationary value ----> d/dx = 0

Hence you need to differentiate your answer to part 1 and equate it to zero to obtain the required solution ;)

Hope it helps :)

--- End quote ---

ok i got it :D thanks ++rep 4 u

here is the answer

d((1-x2)1/2(1+x))/dx  = using quotient rule

U= (1-x2)1/2

du/dx = 0.5* -2x *(1-x2)-1/2


V= 1+x

dv/dx= 1

using the formula

Udv/dx + Vdu/dx =   (1-x2) + (1+x) ((-x)/(1-x2)1/2
                       = (1 - x2-x- x2)/ (1-x2)1/2

since dy/dx = 0

0= 1-2x2-x
2x2+ x - 1=0

(2x-1)(x+1) = 0

x = 1/2 since it is in the right (postive x - axis)



--- Quote from: guowie88 on October 21, 2010, 06:44:02 am ---thk u very much !!! ^^ appreciate it *thumbs up* for u  XD

--- End quote ---
my pleasure  ;D

guowie88:
part 1: the rationalize part i dont understand
can show step by step??
^^ thk

ashish:

--- Quote from: guowie88 on October 21, 2010, 08:03:26 am ---part 1: the rationalize part i dont understand
can show step by step??
^^ thk

--- End quote ---

dy/dx = -(1+x)1/2 / (1-x)1/2 (1+x)2

rationalize

-(1+x)1/2 / (1-x)1/2 (1+x)2  * ((1+x)1/2/(1+x)1/2)

= -(1+x)/ (1-x2)(1+x)2

(1+x) is common in numerator and denominator
 
= -1/ (1-x2)(1+x)

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