Respuesta :

The trinomial is of the form

... a² +2ab +b² = (a+b)²

where a=7x and b=5.

Then the factorization is

... 49x² +70x +25 = (7x +5)²

49x²+70x+25
(49x+35)(49x+35 )
(7x+5)(7x+5)
(7x+5)²