Помогите сделать алгебру 7 класс номер 32.21

1) (3x - 8y)² = (3x)² - 2 * 3x * 8y + (8y)² = 9x² - 48xy + 64y²

2) (7z + 11d)² = (7z)² + 2 * 7z * 11d + (11d)² = 49z² + 154zd + 121d²

3) (3,5t - 4k)² = (3,5t)² - 2 * 3,5t * 4k + (4k)² = 12,25t² - 28tk + 16k²

4) (5k + 1,2t)² = (5k)² + 2 * 5k * 1,2t + (1,2t)² = 25k² + 12kt + 1,44t²

$5)(\frac{2}{3}a-\frac{3}{7}b)^{2}=(\frac{2}{3}a)^{2}-2*\frac{2}{3}a*\frac{3}{7}b+(\frac{3}{7}b)^{2}=\frac{4}{9} a^{2}-\frac{4}{7}ab+\frac{9}{49}b^{2}\\\\6)(\frac{7}{8}c-\frac{4}{7}d)^{2}=(\frac{7}{8}c)^{2}-2*\frac{7}{8}c*\frac{4}{7}d+(\frac{4}{7}d)^{2}=\frac{49}{64}c^{2}-cd+\frac{16}{49}d^{2}$