(1) x2−x1t2−t1=(2⋅5−52)−(2⋅3−32)5−3=10−25−6+92=−122=−6\frac{x_2 - x_1}{t_2 - t_1} = \frac{(2\cdot 5 - 5^2) - (2\cdot 3 - 3^2)}{5 - 3} = \frac{10 - 25 - 6 + 9}{2} = \frac{-12}{2} = -6t2−t1x2−x1=5−3(2⋅5−52)−(2⋅3−32)=210−25−6+9=2−12=−6 (2) x′=2−2tx' = 2 - 2tx′=2−2t (3) x=3x = 3x=3のとき 2−2⋅3=−42 - 2\cdot 3 = -42−2⋅3=−4