1. 9а² - 25b²= (3a)² - (5b)²= (3a-5b)(3a+5b)
2. -81+25m²=(5m)² - 3²= (5m-3)(5m+3)
3. 0,16 - x²= 0,4² - x²= (0,4-x)(0,4+x)
4.144 - 49n²=12² - (7n)²= (12-7n)(12+7n)
5. 4c²-49d²= (2c)² - (7d)²= (2c-7d)(2c+7d)
6. x²y²-0.04 = (xy)² - 0,2²= (xy-0,2)(xy+0,2)
7. a²b²-c²= (ab)² - c²= (ab-c)(ab+c)
8. p²q²-4k² = (pq)² - (2k)² = (pq-2k)(pq+2k)