Respuesta :

This is a perfect square trinomial:
9 x² + 42 x + 49 = ( 3 x )² + 2 · 3 x · 7 + 7² =
= ( 3 x + 7 )² = ( 3 x + 7 ) · ( 3 x + 7 )

Answer:

i think the answer is (3x + 7)(3x + 7)

Step-by-step explanation: