Д) 98² = (100 - 2)² = 100² - 21002 + 2² = 10000 - 400 + 4 = 9604

Е) 198² = (200 - 2)² = 200² - 22002 + 2² = 40000 - 800 + 4 = 39604

Итак, 98² = 9604, а 198² = 39604.