100 a^2-(5a+9)^2=(10а-(5а+9))(10а+(5а+9))=(10а-5а-9)(10а+5а+9)=(5а-9)(15а+9)
2)(3x+1)^2-(4x+3)^2=(3х+1-(4х+3))(3х+1+(4х+3))=(-х-2)(7х+4)=-(х+2)(7х+4)
100 a^2-(5a+9)^2=(10а-(5а+9))(10а+(5а+9))=(10а-5а-9)(10а+5а+9)=(5а-9)(15а+9)
2)(3x+1)^2-(4x+3)^2=(3х+1-(4х+3))(3х+1+(4х+3))=(-х-2)(7х+4)=-(х+2)(7х+4)