A = matrix(18,3,[3705625,1925,1,3724900 ,1930,1,3744225 ,1935,1,3763600,1940,1,3783025,1945,1,3802500,1950,1,3822025,1955,1,3841600,1960,1,3861225,1965,1,3880900,1970,1,3900625,1975,1,3920400,1980,1,3940225,1985,1,3960100,1990,1,3980025,1995,1,4000000,2000,1,4020025,2005,1,4040100,2010,1])
B = A.transpose()*A
Adagger = (B.inverse())*(A.transpose())
y = matrix(18,1,[1902,2044,2221,2355,2512,2017,2150,2499,2916,3144,3468,3741,4042,4339,4455,4599,4704,4799])
x = Adagger*y
var('a,b')
p1 = plot((47941/193800)*(a^2)-(12083533/12920)*a+3432483301/3876,a,1910,2020,color = 'blue');
show(p1)