Consider U = {x|x is a negative real number}. Which is an empty set? {x|x ∈ U and x has a negative cube root} {x|x ∈ U and x has a negative square root} {x|x ∈ U and x is equal to the product of a positive number and –1} {x|x ∈ U and x is equal to the sum of one negative and one positive number}

Which term best describes the association between variables a and b? no association a negative linear association a positive linear association a nonlinear association a scatterplot with an x axis labeled, variable a from zero to ten in increments of two and the y axis labeled, variable b from zero to one hundred forty in increments of twenty with fifteen points in a positive trend.