A= 3x² + 9x=3x(x+3)
B= 3 (x+1) - (2x+7) (x+1)=(x+1)(3-2x-7)=(x+1)(-4-2x)
C=x² + 6x + 9=(x+3)²
D= 25x²- 10x + 1=(5x-1)²
E= 49a² - 1=(7a+1)(7a-1)
F= (5x - 2 )² - 16x²=(5x-2+4x)(5x-2-4x)=(9x-2)(x-2)
G= (1 - 4x )² - (x-2)²=(1-4x+x-2)(1-4x-x+2)=(-3x-1)(-5x+3)