Solve Derivative of sin(cos(cuberoot(x^2-1)))

  • Thread starter Thread starter menal
  • Start date Start date
  • Tags Tags
    Derivative
menal
Messages
42
Reaction score
0

Homework Statement





sin(cos(cuberoot(x^2-1))

i noe you change it to sin(cos(x^2-1)^1/3)
and then (cos(cos(x^2-1)^1/3)(-sin(x^2-1)^1/3)(1/… (2x)
amd then you factor out (x^2-1)^-2/3
and are left with (cos(cos(x^2-1))(-sin(x^2-1))(1/3)(2x)
but what do you do afterwards?
 
Physics news on Phys.org
Greetings! Is the problem asking to take the derivative of sin(cos((x2-1)1/3)? If so, it looks like you're on the right track, although I'm not sure why (x2-1)-2/3 was factored out. Just keep applying the chain rule.

\frac{d}{dx}[\sin(\cos((x^2-1)^{1/3}))]

=\cos(\cos((x^2-1)^{1/3})) \frac{d}{dx}[\cos((x^2-1)^{1/3}))]

=\cos(\cos((x^2-1)^{1/3})) (-\sin((x^2-1)^{1/3}))\frac{d}{dx}[(x^2-1)^{1/3}]

=-\cos(\cos((x^2-1)^{1/3}))\sin((x^2-1)^{1/3})((1/3)(x^2-1)^{-2/3})\frac{d}{dx}[x^2-1]


=-\cos(\cos((x^2-1)^{1/3}))\sin((x^2-1)^{1/3})((1/3)(x^2-1)^{-2/3})(2x)


=\frac{-2x\cos(\cos((x^2-1)^{1/3}))\sin((x^2-1)^{1/3})}{3(x^2-1)^{2/3}}
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
Back
Top