Let's factor in ℝ: 9y2 -25x2 We recognize a difference of two squares: (3y)2 -(5x)2. Apply a2 -b2 = (a -b)·(a + b), with a = 3y and b = 5x This expression can be factorized into: (3y -5x)·(3y + 5x) ▶Factored expression: (3y -5x)·(5x + 3y)