29) 20 + 60t – 80t² = -20 · ...

29) $$20 + 60t – 80t^2 = 20 \cdot \textbf{(1+3t-4t²)}$$

$$20 \cdot (1+3t-4t²) = 20 + 60t – 80t²$$

Ответ: (1+3t-4t²)