what is linear regression with zero correlation what is linear regression? why would you use linear regression when only you know y$ linear regression when only x is known, not y what is linear regression and why is it useful what is linear regression when you only know $xy$, not $y$ what is the solution when only $x is known what is linear regression? when a linear regression is linear when you know only x, what does x mean what type of linear regression method is used how does linear regression work when you only know $y, not directly, what is the optimal correlation when can linear regression be used what is the solution to linear regression which regression method is best used for linear regression? which ols equation is the simplest? what is the problem in linear regression how to calculate linear regression equations when to use linear regression when only knowing x in x