Differentiation of Implicit Functions
[39/79%]. Find at .
An equation , having as a solution a pair of numbers , defines in a neighborhood of the number the quantity as a function of , if the partial derivative is nonzero at the point and continuous in a neighborhood of it. The successive derivatives of with respect to can be obtained from the equalities:
In a similar way one can also compute the derivatives of implicit functions given by a single equation in several variables.
If several implicit functions are given by several equations, then in computing the derivatives it is sometimes convenient to use differentials. Here one should keep in mind that the higher-order differentials of those variables taken as independent are equal to zero.
. Find for which .
. Find for .
. Find .
. Find and .
. Find at , .
. Find .
. Find .
. Regarding here as the independent variable and as a function, take the fourth derivative of both sides of the equation.
For the equation at , , the formula does not make it possible to find ; however, can be found here too, from the formula
Find .
. Find at , .
The same question for the equation .
The equations , are given. Find and at , , .
Find and .
From the equations , , find and , if is the independent variable.
From the equations , , find and at the point , if is the independent variable.
, . Find the derivatives of and .
At the point , find the first and second derivatives of and , if , .
. Find .
. Find .
. Find and .
. Find and .
. Find and .
Find , if .
Find , if .
Find at the point , , , if .
Find the second partial derivatives of , if this function of and is defined by the equation .
Show that , if , .
, ; at , we take . Find and .
, , . Find the derivatives of and with respect to .
, , . Find and .
Show that if , then .
The function is given by the formula , where the variables , , and are related by the equation . Determine at the point , when:
the independent variables are and ;
the independent variables are and .
Show that , defined as a function of and by the equation , where is any differentiable function, satisfies the partial differential equation
called the equation of cylindrical surfaces.
Show that , given as a function of and by the equation , satisfies the equation of conical surfaces
Show that, subject to the equations
satisfies the equation
Show that for the equation
is satisfied.
The function of and is given by the equations:
Show that
The equations are given:
Show that