Respuesta :

(4x+1)(x+3)
=(4x+1)(x+3)
=(4x)(x)+(4x)(3)+(1)(x)+(1)(3)=4x2+12x+x+3=4x2+13x+3
8xienv
answer is 4x^2+12x+1x+3 
  combine like term it will be
      4x^2+13x+3