Each term in the second factor is multiplied by each term in the first factor, called the distributive law
x([tex]x^{4}[/tex] - 4x² + 5 ) + 3([tex]x^{4}[/tex] - 4x² + 5)
= [tex]x^{5}[/tex] - 4x³ + 5x + 3[tex]x^{4}[/tex] - 12x² + 15
= [tex]x^{5}[/tex] + 3[tex]x^{4}[/tex] - 4x³ - 12x² + 5x + 15 ← in standard form
