Answer
$45x^{3}+18x^{2}y-5x-2y$
Work Step by Step
$(3x+1)(3x-1)(2y+5x)$
Multiplying $(3x+1)(3x-1),$ it is in the form of $(a+b)(a-b)$
$(a+b)(a-b)= (a^{2}-b^{2})$.
$(3x+1)(3x-1)= (3x)^{2}-1^{2} = 9x^{2}-1$.
$(3x+1)(3x-1)(2y+5x) = (9x^{2}-1)(2y+5x)$
$=18x^{2}y+45x^{3}-2y-5x$
$=45x^{3}+18x^{2}y-5x-2y$
