20. 11,56a⁸ - 9,61b¹⁰ = (3,4a⁴)² - (3,1b⁵)² = (3,4a⁴ - 3,1b⁵)(3,4a⁴ + 3,1b⁵)
Ответ: (3,4a⁴ - 3,1b⁵)(3,4a⁴ + 3,1b⁵)