#(p+3)^2#
#color(white)("XXXX")##= (color(red)(p)+color(blue)(3)))xxcolor(green)((p+3))#
#color(white)("XXXX")##= [color(red)(p)xxcolor(green)((p+3))] + [color(blue)(3)xxcolor(green)((p+3))]#
#color(white)("XXXX")##= [color(red)(p^2+3p)] + [color(blue)(3p+9)]#
#color(white)("XXXX")##= p^2+6p+9#