b(b+5)+(b+6)^2 при b=\frac{2}{7}.

Решим:

$$b(b+5) + (b+6)^2 = b^2 + 5b + b^2 + 12b + 36 = 2b^2 + 17b + 36$$

Подставим $$b=\frac{2}{7}$$

$$2\cdot(\frac{2}{7})^2 + 17(\frac{2}{7}) + 36 = 2\cdot\frac{4}{49} + \frac{34}{7} + 36 = \frac{8}{49} + \frac{238}{49} + \frac{1764}{49} = \frac{2010}{49} = 41\frac{1}{49}$$

Ответ: $$41\frac{1}{49}$$