How do you differentiate arcsin(sqrtx)?

1 Answer
Oct 14, 2016

1/(2sqrt(x(1-x))

Explanation:

Let color(green)(g(x)=sqrt(x)) and f(x)=arcsinx
Thencolor(blue)(f(color(green)(g(x)))=arcsinsqrtx)

Since the given function is a composite function we should differentiate using chain rule.

color(red)(f(g(x))')=color(red)(f')(color(green)(g(x)))*color(red)(g'(x))

Let us compute color(red)(f'(color(green)(g(x)))) and color(red)(g'(x))

f(x)=arcsinx
f'(x)=1/(sqrt(1-x^2))
color(red)(f'(color(green)(g(x)))=1/(sqrt(1-color(green)(g(x))^2))
f'(color(green)(g(x)))=1/(sqrt(1-color(green)(sqrtx)^2))
color(red)(f'(g(x))=1/(sqrt(1-x)))

color(red)(g'(x))=?

color(green)(g(x)=sqrtx)
color(red)(g'(x)=1/(2sqrtx))

color(red)(f(g(x))')=color(red)(f'(g(x)))*color(red)(g'(x))
color(red)(f(g(x))')=1/(sqrt(1-x))*1/(2sqrtx)
color(red)(f(g(x))')=1/(2sqrt(x(1-x)))

Therefore,
color(blue)((arcsinsqrtx)'=1/(2sqrt(x(1-x)))