co2_2000ppm = roots([A(1),A(2),A(3)-2000])
x1=[year.^2,year,year.^0];
A1 = inv(x1'*x1)*x1'*year;
plot(year,CO2,'b-',year,x1*A,'r');
xlabel('year');
ylabel('CO2 ppm');
title('Predicted Increase of CO2 Levels')
grid