1) Пусть M - середина.
Xm = (Xa+Xb)/2 = (5-1)/2 = 2
Ym = (Ya+Yb)/2 = (8+4)/2 = 6
Zm = (Za+Zb)/2 = (4-6)/2 = -1
M(2,6,-1)
2) f'(x) = (sinx^2)' * ln3x + sinx^2 * (ln3x)' = cosx^2 *(x^2)' * ln3x + sinx^2 * 1/(3x) * (3x)' = cosx^2 * 2x * ln3x + sinx^2 *1/(3x) * 3