Question

Answer 1

`a,`

`3x(x^2-5x+7)`

`= 3x*x^2+3x*(-5x)+3x*7`

`= 3x^3-15x^2+21x`

`b,`

`(x+4)(-x^2+6x+5)`

`= x(-x^2+6x+5)+4(-x^2+6x+5)`

`= -x^3+6x^2+5x-4x^2+24x+20`

`= -x^3+2x^2+29x+20`

Answer 2

A=3x^3-15x^2+21x

B=-x^3+6x^2+5x-4x^2+24x+20

  =-x^3+2x^2+29x+20

Answer 3

a: =3x^3-15x^2+21x

b: =-x^3+6x^2+5x-4x^2+24x+20

=-x^3+2x^2+29x+20