Perhaps you mean that for any integers x and y, x > y, x² - y², 2xy, and x² + y² form a Pythagorean triple. If GCF(x, y) = 1, the triple is primitive.
For x = 5, y = 2, the triple is 21, 20, 29, or from smallest to largest,
20, 21, 29 âś
Let's just check
20² + 21² = 841= 29²