Answer:
[tex] 2(3u + 5 \sqrt{y} )(3u - 5 \sqrt{y} )[/tex]
Step-by-step explanation:
[tex]18 {u}^{2} - 50y \\ \\ = 2[9 {u}^{2} - 25y] \\ \\ = 2[(3 {u})^{2} - (5 \sqrt{y} )^{2} ] \\ \\ = 2(3u + 5 \sqrt{y} )(3u - 5 \sqrt{y} )[/tex]