MATH-UA 211 Lecture Notes - Lecture 1: Equilibrium Point, Demand Curve
13 Sep 2016
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A function is like a rule or a machine: when you put in an x value, it does what f says and out comes f(x), or y. Textbook definition: a function f is a rule that assigns to each element x in a set a exactly one element, called f(x), in a set b. Plug in -2 for x; (-2)2 = 4; f(-2) = 4. The domain of f is the set of all possible inputs (x-values), and the range of f is the set of all possible outputs (y-values). So, each x can correspond to exactly one y. Mary sells necklaces at the beach for a piece. Revenue: (necklaces sold) x (price of a necklace) Let q be the # of necklaces sold, and let r(q) be revenue. Integer powers: x2, x3: linear: x, 2x-1. 2: polynomials: 2x2-1 (quadratic), x3+x (cubic), x5-3x4+1, roots: , exponential: (1. 03)x, 2x, ex, logarithmic: log2, ln.
