Derivative of ln2(x)\ln^{2}\left(x\right)

The calculator will find the derivative of ln2(x)\ln^{2}\left(x\right), with steps shown.

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Your Input

Find ddx(ln2(x))\frac{d}{dx} \left(\ln^{2}\left(x\right)\right).

Solution

The function ln2(x)\ln^{2}\left(x\right) is the composition f(g(x))f{\left(g{\left(x \right)} \right)} of two functions f(u)=u2f{\left(u \right)} = u^{2} and g(x)=ln(x)g{\left(x \right)} = \ln\left(x\right).

Apply the chain rule ddx(f(g(x)))=ddu(f(u))ddx(g(x))\frac{d}{dx} \left(f{\left(g{\left(x \right)} \right)}\right) = \frac{d}{du} \left(f{\left(u \right)}\right) \frac{d}{dx} \left(g{\left(x \right)}\right):

(ddx(ln2(x)))=(ddu(u2)ddx(ln(x))){\color{red}\left(\frac{d}{dx} \left(\ln^{2}\left(x\right)\right)\right)} = {\color{red}\left(\frac{d}{du} \left(u^{2}\right) \frac{d}{dx} \left(\ln\left(x\right)\right)\right)}

Apply the power rule ddu(un)=nun1\frac{d}{du} \left(u^{n}\right) = n u^{n - 1} with n=2n = 2:

(ddu(u2))ddx(ln(x))=(2u)ddx(ln(x)){\color{red}\left(\frac{d}{du} \left(u^{2}\right)\right)} \frac{d}{dx} \left(\ln\left(x\right)\right) = {\color{red}\left(2 u\right)} \frac{d}{dx} \left(\ln\left(x\right)\right)

Return to the old variable:

2(u)ddx(ln(x))=2(ln(x))ddx(ln(x))2 {\color{red}\left(u\right)} \frac{d}{dx} \left(\ln\left(x\right)\right) = 2 {\color{red}\left(\ln\left(x\right)\right)} \frac{d}{dx} \left(\ln\left(x\right)\right)

The derivative of the natural logarithm is ddx(ln(x))=1x\frac{d}{dx} \left(\ln\left(x\right)\right) = \frac{1}{x}:

2ln(x)(ddx(ln(x)))=2ln(x)(1x)2 \ln\left(x\right) {\color{red}\left(\frac{d}{dx} \left(\ln\left(x\right)\right)\right)} = 2 \ln\left(x\right) {\color{red}\left(\frac{1}{x}\right)}

Thus, ddx(ln2(x))=2ln(x)x\frac{d}{dx} \left(\ln^{2}\left(x\right)\right) = \frac{2 \ln\left(x\right)}{x}.

Answer

ddx(ln2(x))=2ln(x)x\frac{d}{dx} \left(\ln^{2}\left(x\right)\right) = \frac{2 \ln\left(x\right)}{x}A