Answer 1

x² + 6xy + 9y² + x + 3y 

= [(x)² + 2 × x × 3y + (3y)²] + (x + 3y) 

= [x + 3y]² + (x + 3y) 

= (x + 3y) (x + 3y) + (x + 3y)

= (x + 3y) (x + 3y + 1)