How many numbers are reciprocals of themselves?

2

Explanation:

In short terms, there are two numbers that are reciprocals of themselves, 1 and -1.  According to euler's identity, e^(-i*2*pi) is a reciprocal of itself, but I believe that is beyond the scope of this question.

answer is the third choice:

3x^5+4x^4+x^3+2x^2-10x-7=0

step-by-step explanation:

hello from mrbilldoesmath!

answer:

the domain is the set { -2, 0, 2, 3}

discussion:

the domain is the set of x values in the ordered pairs (x,y). taking the x, or first component, of each ordered pair gives   -2, 0, 2, 3.

you,

mrb