#### Video: Predator-prey systems

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Video tutorial on how to determine which variable represents the predator population, and which represents the prey population, how to determine if the predator or prey populations are effected by any other food source than the other species (carrying capacity), how to determine whether the system is one of cooperation, competition, or predator-prey, and how to solve the system of differential equations for equilibrium solutions, and then interpret those equilibrium solutions.

#### Volume of a Double Integral - Reimann Sums

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Video Tutorial: Using Riemann sums to approximate the volume that lies above the given rectangular region defined by the given x-interval by the given y-interval, and below the given function. You'll divide the interval into rectangles and then find the coordinate points that define the upper right-hand corner of each of those rectangles. Then you&'ll evaluate the original function at each coordinate point, take the sum of those values, and multiply that sum by delta A, which is the area of one of the rectangles.