Chain
rule: partial derivative
Chain rule: identity involving partial derivatives Chain rule & partial derivatives Partial derivatives and PDEs tutorial Partial derivatives and error estimation 
Taylor
polynomials: functions of two variables
Leibniz' rule: Integration via differentiation Evaluating challenging integrals via differentiation: Leibniz rule 
How
to find critical points of functions
Critical points + 2nd derivative test: Multivariable
calculus How to find and classify critical points of functions 
Lagrange
multipliers Extreme values of a function subject to a
constraint Lagrange multiplier example: Minimizing a function subject to a constraint Multivariable Calculus: Directional derivative of $f(x,y)$ Lagrange multipliers example 
Vector
Calculus Divergence of a vector field Curl of a vector field (ex. no.1 & 2) 
Path
integral (scalar line integral) from vector calculus
Line integral example in 3Dspace Line integral from vector calculus over a closed curve Line integral from vector calculus over a closed curve Line integral example from Vector Calculus 
Double
integral tutorial
Double integrals in polar coordinates Double integrals and area 
Double integrals Volume between two surfaces Volume of a tetrahedron Reversing the order of integration Reversing order in double integrals 
Homogeneous
first order ordinary differential equation
Solution to a 2nd order, linear homogeneous ODE with
repeated roots 2nd order ODE with constant coefficients: simple method of solution 2nd order ODE with constant coefficients: nonstandard method of solution 
Intro
to Laplace transform
Laplace transform + differential equations First shifting theorem of Laplace transforms Laplace Transform: First Shifting Theorem 
Second
shifting theorem of Laplace transforms
Laplace Transform: Second Shifting Theorem Laplace Transform of tf(t) 
Intro to
Fourier series and how to calculate them
How to compute a Fourier series: an example Fourier series + differential equations 

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