(n^2+1)^2
(x^4-x^2)^2
(y^4+y^3)^2
(-3a+4b^3)^2

(n² + 1)² = (n²)² + 2 * n² * 1 + 1² = n⁴ + 2n² + 1

(x⁴ - x²)² = (x⁴)² - 2 * x⁴ * x² + (x²)² = x⁸ - 2x⁶ + x⁴

(y⁴ + y³)² = (y⁴)² + 2 * y⁴ * y³ + (y³)² = y⁸ + 2y⁷ + y⁶

(- 3a + 4b³)² = (4b³ - 3a)² = (4b³)² - 2 * 4b³ * 3a + (3a)² = 16b⁶ - 24ab³ + 9a²