We have a = {a+b√2 | a, b∈z}. prove that a is a commutative ring in relation with addition and multiplication of real numbers.

Alcoa was $10.02 a share yesterday. today it is at $9.75 a share. if you own 50 shares, did ou have capital gain or loss ? how much of a gain or loss did you have ? express the capital gain/loss as a percent of the original price

Aof 12 , we to a of 4 to on a .of 4 be ?

Is the response to the survey question "did you smoke in the last week question mark "response to the survey question "did you smoke in the last week? " a discrete random variable, a continuous random variable, or not a random variable?