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Calculus III β€” Multivariable Calculus

Functions of several variables, in 3D: gradients, tangent planes, double and triple integrals, and the vector calculus that ties circulation, flux, and divergence into one family of theorems -- built on surfaces you can actually rotate, not just read about.

Free to read now, no account needed: Readiness review. Create a free account to open the other chapters, take the quizzes and keep your progress.

1 Vectors and the geometry of space πŸ”’

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  • 3D coordinates and distance ~10 min
  • Vectors in space ~10 min
  • Vector operations ~10 min
  • The dot product ~12 min
  • Projections and work ~12 min
  • The cross product ~12 min
  • Triple products and volume ~10 min
  • Lines in space ~10 min
  • Planes in space ~10 min
  • Distances between points, lines, and planes ~12 min
  • Cylinders and quadric surfaces ~14 min

2 Vector-valued functions and motion πŸ”’

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  • Vector-valued functions ~10 min
  • Limits and continuity of r(t) ~8 min
  • Derivatives of vector functions ~10 min
  • Differentiation rules for vector functions ~10 min
  • Integrals of vector functions ~9 min
  • Projectile and orbital motion ~12 min
  • Arc length of a space curve ~9 min
  • The unit tangent and arc-length parametrization ~10 min
  • Curvature and the normal vector ~10 min
  • TNB, torsion, and tangential/normal acceleration ~12 min

3 Functions of several variables πŸ”’

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  • Functions of two and three variables ~10 min
  • Domain and range ~12 min
  • Graphs and surfaces ~12 min
  • Level curves and contour maps ~12 min
  • Level surfaces ~10 min
  • Limits in two variables ~12 min
  • Paths and nonexistent limits ~12 min
  • Continuity of multivariable functions ~10 min
  • A first look at partial rates ~10 min

4 Partial derivatives πŸ”’

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  • Partial derivatives ~12 min
  • The geometric meaning of a partial derivative ~10 min
  • Higher-order partials and Clairaut's theorem ~12 min
  • Differentiability and local linearity ~13 min
  • Tangent planes ~11 min
  • Linear approximation and differentials ~12 min
  • The multivariable chain rule ~12 min
  • Implicit differentiation in several variables ~11 min
  • Taylor's theorem in two variables ~13 min
  • When partials exist but the function isn't differentiable ~12 min

5 The gradient and directional derivatives πŸ”’

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  • Directional derivatives ~12 min
  • The gradient vector ~12 min
  • The gradient as the direction of steepest ascent ~10 min
  • The gradient is perpendicular to level curves ~10 min
  • Gradients and level surfaces ~10 min
  • Normal lines and tangent planes via the gradient ~12 min
  • Gradient descent ~12 min
  • The gradient in three variables ~10 min

6 Optimization πŸ”’

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  • Critical points ~10 min
  • The second derivative test ~12 min
  • Local versus absolute extrema ~9 min
  • Extrema on closed, bounded regions ~13 min
  • Applied optimization ~12 min
  • Constrained optimization ~10 min
  • Lagrange multipliers ~13 min
  • Lagrange multipliers with two constraints ~12 min
  • Least squares and applications ~13 min

7 Double integrals πŸ”’

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  • Double integrals over rectangles ~10 min
  • Iterated integrals and Fubini's theorem ~12 min
  • Double integrals over general regions ~13 min
  • Reversing the order of integration ~12 min
  • Area and average value ~10 min
  • Double integrals in polar coordinates ~13 min
  • Surface area ~12 min
  • Mass and density ~10 min
  • Moments and center of mass ~12 min
  • Moments of inertia ~12 min

8 Triple integrals and coordinate systems πŸ”’

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  • Triple Integrals ~12 min
  • General Solid Regions ~12 min
  • The Six Orders of Integration ~12 min
  • Cylindrical Coordinates ~12 min
  • Spherical Coordinates ~13 min
  • Choosing a coordinate system ~11 min
  • The Jacobian ~13 min
  • Change of variables in double integrals ~13 min
  • Change of variables in triple integrals ~13 min

9 Vector fields and line integrals πŸ”’

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  • Vector fields ~10 min
  • Gradient and conservative fields ~10 min
  • Potential functions ~12 min
  • Line integrals of scalar functions ~12 min
  • Line integrals of vector fields and work ~12 min
  • The Fundamental Theorem for line integrals ~10 min
  • Independence of path ~10 min
  • The 2D test for conservative fields ~10 min
  • Circulation and flux in the plane ~12 min
  • Green's theorem ~12 min

10 Surface integrals and flux πŸ”’

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  • Parametric surfaces ~12 min
  • Surfaces of revolution ~12 min
  • Tangent planes to parametric surfaces ~12 min
  • Surface area ~12 min
  • Surface integrals of scalar functions ~12 min
  • Orientation of a surface ~10 min
  • Flux integrals ~12 min
  • Applications of flux ~12 min

11 The fundamental theorems of vector calculus πŸ”’

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  • Divergence ~12 min
  • Curl ~12 min
  • The 3D conservative-field test ~12 min
  • Green's theorem, two forms ~12 min
  • Stokes' theorem ~14 min
  • Using Stokes' theorem to change the surface ~12 min
  • The divergence theorem ~14 min
  • One theorem in four disguises ~12 min
  • Applications in physics and electromagnetism ~14 min