An operation * is defined on the set of real numbers, R, by x * y = x + y +3xy. If * is commutative,: 1) Find the identity element e of R under the operation *.
2) Determine the inverse of an element x ∈ R, under the operation *.
3) Find the value x ∈ R, for which no inverse exists.

What is the exact volume of the cylinder? 16in going into the middle of the top of the cylinder and 40in in height a) 25,600(pi)3 b)10,240(pi)3 c)1280(pi)3 d)640(pi)3

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 slope simplify your answer and write it as a proper fraction, improper fraction, or integer