Determine whether each of the binary relation R defined on the given sets A is reflexive, symmetric, antisymmetric, or transitive. If a relation has a certain property, prove this is so; otherwise provide a counterexample to show that it does not. (a) A = Z: (a, b) E R if and only if ab > 0. (b) A = R: (a, b) R if and only if a^2=b^2 (c) A = N: (a, be R if and only if a/b is an integer.

The decibel level of sound is 50 db greater on a busy street than in a quiet room where the intensity of sound is watt/m2. the level of sound in the quiet room is db, and the intensity of sound in the busy street is watt/m2. use the formula , where is the sound level in decibels, i is the intensity of sound, and is the smallest sound intensity that can be heard by the human ear (roughly equal to watts/m2).

What is the point-slope form of the equation for the line with a slope of -2 that passes through (1,4)?

At the county fair, the baxter family bought 6 hot dogs and 4 juice drinks for $12.90. the farley family bought 3 hot dogs and 4 juice drinks for $8.55. find the price of a hot dog and the price of a juice drink.