Помогите номер 10, пожалуйста

${y}^{2} - {b}^{2} + 4b - 4 \\ {y}^{2} = {b}^{2} - 4b + 4 \\ {y}^{2} = {(b - 2)}^{2} \\ y = b - 2$
${c}^{2} - \frac{2c}{3} + \frac{1}{9} - \frac{1}{9} \times {y}^{2} = 0 \\ \frac{1}{9} \times {y}^{2} = {c}^{2} - \frac{2c}{3} + \frac{1}{9}$
Перемножим обе части на 9
${y}^{2} = 9 {c}^{2} - 6c + 1 \\ y = \sqrt{9 {c}^{2} - 6c + 1}$