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Differential Calculus help

Hi,

I was wondering if anyone could help me with a few of these questions?

a) Find the derivative of y=secxtanxy=sec x tan x

Answer = secx(2sec2x−1)secx(2sec^2x - 1) but I get secx(sec2x+tan2x)sec x(sec^2x + tan^2x)?


b) If y=cosec3x,y=cosec^3x, show that dy/dx+3ycotx=0dy/dx + 3y cot x = 0

c) If y=x2lnx,y=x^2lnx, show that dy/dx=xln(ex2)dy/dx = x ln(ex^2) but I get x + 2x lnx?


Thanks :smile:
(edited 13 years ago)
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Avatar for Pheylan
Pheylan
Original post by ScottishShortiex
Find the derivative of y=secxtanxy=sec x tan x

Answer = secx(2sec2x−1)secx(2sec^2x - 1) but I get secx(sec2x+tan2x)sec x(sec^2x + tan^2x)?
rewrite tan^2(x) in terms of sec^2(x)
Original post by Pheylan
rewrite tan^2(x) in terms of sec^2(x)


Does that mean that tan2x=sec2x−1tan^2x = sec^2x - 1

Thanks :smile:

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