Solve tau = l / r

Simplify

τ = \frac{l}{r}

Find the first partial derivative by treating the variable r as a constant and differentiating with respect to l

\frac{\partial τ}{\partial l} = \frac{\partial}{\partial l} (\frac{l}{r})

Use differentiation rule \frac{\partial}{\partial x} (\frac{f ( x )}{g ( x )}) = \frac{\frac{\partial}{\partial x} ( f ( x )) \times g ( x ) - f ( x ) \times \frac{\partial}{\partial x} ( g ( x ) )}{( g ( x ) ) ^{2}}

\frac{\partial τ}{\partial l} = \frac{\frac{\partial}{\partial l} ( l ) r - l \times \frac{\partial}{\partial l} ( r )}{r ^{2}}

Use \frac{\partial}{\partial x} x^{n} = n x^{n - 1} to find derivative

\frac{\partial τ}{\partial l} = \frac{1 \times r - l \times \frac{\partial}{\partial l} ( r )}{r ^{2}}

Use \frac{\partial}{\partial x} (c) = 0 to find derivative

\frac{\partial τ}{\partial l} = \frac{1 \times r - l \times 0}{r ^{2}}

Any expression multiplied by 1 remains the same

\frac{\partial τ}{\partial l} = \frac{r - l \times 0}{r ^{2}}

Any expression multiplied by 0 equals 0

\frac{\partial τ}{\partial l} = \frac{r - 0}{r ^{2}}

Removing 0 doesn't change the value,so remove it from the expression

\frac{\partial τ}{\partial l} = \frac{r}{r ^{2}}

Solution

More Steps

\frac{\partial τ}{\partial l} = \frac{1}{r}

Function