9-4x²-48xy-144у² = 9 - (4x²+48xy+144у²) = - ( (4x²+48xy+144у²) - 9) = -( (2х+12у)² - 3²) = - (2х+12у-3)*(2х+12у+3)
9-4x²-48xy-144у² = 9 - (4x²+48xy+144у²) = - ( (4x²+48xy+144у²) - 9) = -( (2х+12у)² - 3²) = - (2х+12у-3)*(2х+12у+3)