How do you find the derivative of lnsqrt xlnx?

1 Answer
Apr 9, 2015

In general
(d ln(a))/(da) = 1/adln(a)da=1a

Specifically if a=sqrt(x)a=x
(d ln(sqrt(x)))/(d sqrt(x)) = 1/sqrt(x)dln(x)dx=1x

sqrt(x) = x^(1/2)x=x12

(d sqrt(x))/dx = 1/2 x^(-1/2) = 1/(2sqrt(x))dxdx=12x12=12x

(d ln(sqrt(x)))/(dx) = (d ln(sqrt(x)))/(d sqrt(x)) * (d sqrt(x))/dxdln(x)dx=dln(x)dxdxdx

= 1/sqrt(x) * 1/(2sqrt(x))=1x12x

= 1/(2x)=12x

That is, the derivative of ln sqrt(x)lnx
is
1/(2x)12x