$$x^4*x^5=x^9$$
$${{\mathtt{x}}}^{{\mathtt{4}}}{\mathtt{\,\times\,}}{{\mathtt{x}}}^{{\mathtt{3}}} = {{\mathtt{x}}}^{{\mathtt{7}}}$$
$$x^4*15=15x^4$$
$$x*x^5=x^6$$
$$x*x^3=x^4$$
$$x*15=15x$$
$$5*x^5=5x^5$$
$$5*x^3=5x^3$$
$$5*15=75$$
simplify gives you $$x^9+x^7+x^6+5x^5+16x^4+5x^3+75$$
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+128475 The constant term is just the product of the two constant terms in each polynomial....thus 15 * 5 = 75
$$x^4*x^5=x^9$$
$${{\mathtt{x}}}^{{\mathtt{4}}}{\mathtt{\,\times\,}}{{\mathtt{x}}}^{{\mathtt{3}}} = {{\mathtt{x}}}^{{\mathtt{7}}}$$
$$x^4*15=15x^4$$
$$x*x^5=x^6$$
$$x*x^3=x^4$$
$$x*15=15x$$
$$5*x^5=5x^5$$
$$5*x^3=5x^3$$
$$5*15=75$$
simplify gives you $$x^9+x^7+x^6+5x^5+16x^4+5x^3+75$$
