There are 6 people at a party. if every person has to shake everyone's hand exactly once, how many handshakes is there all together?

What's the difference between: x≥0 and nonnegative integer. ?

17. a researcher measures three variables, x, y, and z for each individual in a sample of n = 20. the pearson correlations for this sample are rxy = 0.6, rxz = 0.4, and ryz = 0.7. a. find the partial correlation between x and y, holding z constant. b. find the partial correlation between x and z, holding y constant. (hint: simply switch the labels for the variables y and z to correspond with the labels in the equation.) gravetter, frederick j. statistics for the behavioral sciences (p. 526). cengage learning. kindle edition.

Asystem of equations has 1 solution. if 4x-y=5 is one of the equations , which could be the other equation ?