Calculate the variance of a data set: 8, 12, 15, 18, 20
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What is the equation of an ellipse with a major axis of length 10 units, minor axis of length 6 units, centered at (2, -3), and tilted at an angle of 45 degrees with the positive x-axis?
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What is the derivative of sin(2x) + cos(3x) - tan(x) - cot(4x) + sec(5x) - csc(6x)?