Respuesta :
multiply the parentheses then collect like terms
(x+4y+z) (x-7y)
x^2-7xy+4xy-28y^2+xz-7yz
x^2-3xy-28y^2+xz-7yz
(x+4y+z) (x-7y)
x^2-7xy+4xy-28y^2+xz-7yz
x^2-3xy-28y^2+xz-7yz