ANSWER
[tex]48 {x}^{4} + 60{x}^{2} {y}^{3} + 56 {y}^{6}[/tex]
EXPLANATION
We want expand:
[tex](12x^2+8y^3)(4x^2+7y^3)[/tex]
We expand using the distributive to obtain:
[tex]12 {x}^{2} (4 {x}^{2} + 7 {y}^{3} ) + 8 {y}^{3} (4 {x}^{2} + 7 {y}^{3} )[/tex]
[tex]48 {x}^{4} + 28 {x}^{2} {y}^{3} + 32{x}^{2} {y}^{3} + 56 {y}^{6}[/tex]
Simplify further by combining the two terms in the middle:
[tex]48 {x}^{4} + 60{x}^{2} {y}^{3} + 56 {y}^{6}[/tex]
