Разложите на множители: (3x+1)^2-(4x+3)^2.

\[(3x + 1)^{2} - (4x + 3)^{2} =\]

\[= \left( 3x + 1 - (4x + 3) \right)(3x + 1 + 4x + 3) =\]

\[= (3x + 1 - 4x - 3)(7x + 4) =\]

\[= ( - x - 2)(7x + 4) =\]

\[= - (x + 2)(7x + 4).\]