What is the derivative of y = (xsqrt(x^2 + 1))/(x + 1)^(2/3)y=xx2+1(x+1)23?

1 Answer
Aug 23, 2017

dy/dx = (xsqrt(x^2 + 1))/(x + 1)^(2/3)(1/x + x/(x^2 + 1) - 2/(3(x + 1)))dydx=xx2+1(x+1)23(1x+xx2+123(x+1))

Explanation:

We let

y = (xsqrt(x^2 + 1))/(x + 1)^(2/3)y=xx2+1(x+1)23

Now using logarithmic differentiation, we have:

lny = ln((xsqrt(x^2 + 1))/(x + 1)^(2/3))lny=ln(xx2+1(x+1)23)

We can now use laws of logarithms to simplify.

lny = ln(x) + ln(x^2 + 1)^(1/2) - ln(x + 1)^(2/3)lny=ln(x)+ln(x2+1)12ln(x+1)23

lny = ln(x) + 1/2ln(x^2 + 1) - 2/3ln(x + 1)lny=ln(x)+12ln(x2+1)23ln(x+1)

Now differentiate term by term .

1/y(dy/dx) = 1/x + (2x)/(2(x^2 + 1)) - 2/(3(x+ 1))1y(dydx)=1x+2x2(x2+1)23(x+1)

dy/dx = y(1/x + x/(x^2 + 1) - 2/(3(x + 1)))dydx=y(1x+xx2+123(x+1))

dy/dx = (xsqrt(x^2 + 1))/(x + 1)^(2/3)(1/x + x/(x^2 + 1) - 2/(3(x + 1)))dydx=xx2+1(x+1)23(1x+xx2+123(x+1))

Hopefully this helps!