Answer:
D
Step-by-step explanation:
a perfect square trinomial is
[tex]a^2x^2\pm2(ab)xy+b^2y^2[/tex]
factorized is
[tex](ax\pm by)^2[/tex]
so as you can see option A and B can't be, because they have -49y^2 and it has to be plus
so the other options are C and D
in the trinomial a=4 and b=\pm 7
the roots of a^2 and b^2
[tex]\pm2abxy=\pm2(4)(7)xy\\\\=\pm56xy[/tex]
so it's option d with b=-7
[tex]16x^2-56xy+49y^2[/tex]
