25 (9-4x)-4x(9-4x) adalah...

[tex]25(9 - 4 {x}^{2} ) - 4 {x}^{2} (9 - 4 {x}^{2} ) \\ = 225 - 100 {x}^{2} -225{x}^{2} + 16 {x}^{4} \\ = 225 - 325 {x}^{2} + 16 {x}^{4} \\ = 16 {x}^{4} - 325 {x}^{2} + 225[/tex]
Semoga dapat dipahami

225-100x"-36-16x⁴
189-100x"-16x⁴