a) \(54^2 - 44^2 = (54 - 44)(54 + 44) = 10 \cdot 98 = 980\)
б) \(63.9^2 - 63.8^2 = (63.9 - 63.8)(63.9 + 63.8) = 0.1 \cdot 127.7 = 12.77\)
в) \(\frac{27^2 - 22^2}{70} = \frac{(27 - 22)(27 + 22)}{70} = \frac{5 \cdot 49}{70} = \frac{245}{70} = 3.5\)