1) y = 5 - 3lnx, x₀ = 4
y` = - 3/x
y`(4) = - 3/4
2) y = x³/2 - ln(2x), x₀ = 2
y` = (3x²)/2 - 2/(2x) = (3x²)/2 - 1/x
y`(2) = (3*4)/2 - 1/2 = 11/2 = 5,5
3) f(x) = 6cos(π/3 - 3x) = 6cos(3x - π/3), x₀ = π/6
f1(x) = - 18sin(3x - π/3)
f`(π/6) = - 18sin(3*π/6 - π/3) = - 18sin(π/2 - π/3) = - 18sin(π/6) = - 18*(1/2) = - 9