The normal equation for linear regression is :
β=(XTX)-1XTY
This is also known as the closed-form solution for a linear regression model.
where,
Y=βTX is the equation that represents the model for the linear regression,
Y is the dependent variable or target column,
β is the vector of the estimates of the regression coefficient, which is arrived at using the normal equation,
X is the feature matrix that contains all the features in the form of columns. The thing to note down here is that the first column in the X matrix consists of all 1s, to incorporate the offset value for the regression line.