Решение:

1. a) (5 + x)² $$ (5 + x)^2 = 5^2 + 2 \cdot 5 \cdot x + x^2 = 25 + 10x + x^2 $$
2. б) (1 - 3x)² $$ (1 - 3x)^2 = 1^2 - 2 \cdot 1 \cdot 3x + (3x)^2 = 1 - 6x + 9x^2 $$
3. в) (3a – 10b)² $$ (3a - 10b)^2 = (3a)^2 - 2 \cdot 3a \cdot 10b + (10b)^2 = 9a^2 - 60ab + 100b^2 $$
4. г) (x² + 4)² $$ (x^2 + 4)^2 = (x^2)^2 + 2 \cdot x^2 \cdot 4 + 4^2 = x^4 + 8x^2 + 16 $$
5. д) (у + 15)² $$ (y + 15)^2 = y^2 + 2 \cdot y \cdot 15 + 15^2 = y^2 + 30y + 225 $$
6. е) (5x – 0,2)² $$ (5x - 0.2)^2 = (5x)^2 - 2 \cdot 5x \cdot 0.2 + (0.2)^2 = 25x^2 - 2x + 0.04 $$
7. ж) (−2a + 7b)² $$ (-2a + 7b)^2 = (-2a)^2 + 2 \cdot (-2a) \cdot 7b + (7b)^2 = 4a^2 - 28ab + 49b^2 $$
8. з) (a³+b⁴)² $$ (a^3 + b^4)^2 = (a^3)^2 + 2 \cdot a^3 \cdot b^4 + (b^4)^2 = a^6 + 2a^3b^4 + b^8 $$
9. и) (3x - 1/3)² $$ \left(3x - \frac{1}{3}\right)^2 = (3x)^2 - 2 \cdot 3x \cdot \frac{1}{3} + \left(\frac{1}{3}\right)^2 = 9x^2 - 2x + \frac{1}{9} $$
10. к) (-6x - 1)² $$ (-6x - 1)^2 = (-6x)^2 + 2 \cdot (-6x) \cdot (-1) + (-1)^2 = 36x^2 + 12x + 1 $$
11. л) (4а - b²)² $$ (4a - b^2)^2 = (4a)^2 - 2 \cdot 4a \cdot b^2 + (b^2)^2 = 16a^2 - 8ab^2 + b^4 $$
12. м) (x⁴ - 9x)² $$ (x^4 - 9x)^2 = (x^4)^2 - 2 \cdot x^4 \cdot 9x + (9x)^2 = x^8 - 18x^5 + 81x^2 $$