Answer
$15x^4-47x^2+28$
Work Step by Step
Using $(a+b)(c+d)=ab+ad+bc+bd$ or the FOIL Method, the product of the given expression, $
(5x^2-4)(3x^2-7)
,$ is
\begin{array}{l}\require{cancel}
5x^2(3x^2)+5x^2(-7)-4(3x^2)-4(-7)
\\\\=
15x^4-35x^2-12x^2+28
\\\\=
15x^4-47x^2+28
.\end{array}
