Вот ответ не очень сложно
1. 49 - x² = (7 - x)(7 + x)
2. 4 - x² = (2 - x)(2 + x)
3. 16x² - 9 = (4x - 3)(4x + 3)
4. (5x + 2)² = 25x² + 20x + 4
5. (7x + 1)² = 49x² + 14x + 1
6. 64x² - 9 = (8x - 3)(8x + 3)
7. 25x² - 20x + 4 = (5x - 2)²
8. 16y² + 24y + 9 = (4y + 3)²
9. (0.2y - x)(0.2y + x) = 0.04y² - x²
10. 2x + x² + 1 = (x + 1)²
11. 8x + 16 + x² = (x + 4)²
12. (7 + x)(7 - x) = 49 - x²
13. -y⁸ + x² = (x - y⁴)(x + y⁴)
14. (x + 0.4)² = x² + 0.8x + 0.16
15. (a + 1)(a² - a + 1) = a³ + 1
16. (a - 3)(a² + 3a + 9) = a³ - 27
17. 64 - a³ = (4 - a)(16 + 4a + a²)
18. a³ + 1000 = (a + 10)(a² - 10a + 100)
19. (x - 1)³ = x³ - 3x² + 3x - 1
20. (1 - x)³ = 1 - 3x + 3x² - x³
{ 0.3(x + y) = 22.2
{ 0.4(x - y) = 6.4
{ 0.3x + 0.3y = 22.2
{ 0.4x - 0.4y = 6.4
{ x + y = 74
{ x - y = 16
x = 74 - y
74 - y - y = 16
74 - 2y = 16
2y = 74 - 16
2y = 58
y = 29
x = 74 - 29 = 45