Respuesta :

Answer:

Step-by-step explanation:

You expand the brackets:

  • [tex]3x(x) =3x^{2}[/tex]
  • [tex]3x(7) = 21x[/tex]
  • [tex]-4(x)=-4x[/tex]
  • [tex]-4(+7)=-28[/tex]

Now you simplify and collect like terms:

[tex]3x^{2} (+21x-4x)-28[/tex]

[tex]3x^{2} +17x-28[/tex]

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