N  (            )2
χ2 = ∑   yi --(a+-bxi)
     i=1       σi

tex TeX xi __ tan y a@ b @codemathcodea < b @codemath code i@vareff if(x)@sup2

                        (      )
           -1---       1  x--μ- 2
- - f(x) = σ√2π-e@sup - 2   σ