What is the area of a circle with radius r? (A = πr²)
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Math question: Find the derivative of f(x) = 3x^2 + 5√x + 8ln(x) - 7e^x.
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Math question: What is the equation of an ellipse with a horizontal major axis, center at (h, k), semi-major axis length of a, and semi-minor axis length of b?