## Intermediate Algebra (6th Edition)

$9x^6+15x^4+3x^2+1$
Using $(a+b)(c+d)=ac+ad+bc+bd$ or the FOIL Method, the expression, $(3x^4+1)(3x^2+5)$, is equivalent to \begin{array}{l} 3x^4(3x^2)+3x^4(5)+1(3x^2)+1(5) \\\\= 9x^6+15x^4+3x^2+1 .\end{array}