Qualification > Math

urgent:trigonometric equation help and a few other questions

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Deadly_king:

--- Quote from: lhl_anecar on October 18, 2010, 12:19:00 am ---thanks for the help!! appreciate it loads.. it's really kind of you guys to help me out.
i just have one last question that i am still unsure about and hope u guys can help me out
 which is

using the product rule to find the derivatives of the following..

a)  x^2[?x + (1/?x)]


thanks again!!

--- End quote ---

First you need to expand the brackets and replace square roots by power 1/2.

Let y = x2(x1/2 + 1/x1/2)

Since they all have the same base(x), multiplication implies addition of powers while division implies subtraction of powers ;)

y = x(2+1/2) + x(2-1/2) ----> y = x5/2 + x3/2

From here it's easy to differentiate : dy/dx = 5/2 x3/2 + 3/2 x1/2

The required solution can be simplifies as (5x3/2 + 3x1/2)/2

Hope it helps :)

Deadly_king:

--- Quote from: lhl_anecar on October 18, 2010, 12:22:27 am ---R=(e^t+1)(t-lnt)  

i missed out the = sign, sorry about that,i just don't seem to get how to differentiate ln. please help. thanks!!! :)


--- End quote ---

Is it R = (e(t+1))(t - lnt) or R = (et + 1)(t - lnt) ???

lhl_anecar:

--- Quote from: Deadly_king on October 19, 2010, 06:57:31 am ---Is it R = (e(t+1))(t - lnt) or R = (et + 1)(t - lnt) ???

--- End quote ---

R = (et + 1)(t - lnt) it is this one..  ;D sorry about the typing error. thanks!!!

Freaked12:
well we can use the product rule

u = e^t + 1
u' = e^t

v = t - ln t
v' = 1 - 1/t

dR/dt = u'v + uv'
= e^t (t - ln t) + (e^t +1).(1-1/t)

Tell me if this is wrong.

lhl_anecar:
y=(x^5)(e^x) + 3xlnx

how do i solve this?? i made a mistake typing the previous question... my bad, made the whole question more difficult..
someone..please help me out, again.. thanks!! thank you very very much......

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