$$(3f+8)^2+(5f-2) = (9f^2 + 2 \cdot 3f \cdot 8 + 64) + 5f - 2 = 9f^2 + 48f + 64 + 5f - 2 = 9f^2 + 53f + 62$$
Ответ: $$9f^2 + 53f + 62$$