y = 4 * x * (x^(1/2) + 2) = 4 * x^(3/2) + 8 * x
Тогда
y' = (4 * x^(3/2) + 8 * x)' = 4 * 3/2 * x^(1/2) + 8 = 6 * x^(1/2) + 8
y'(4) = 6 * 4^(1/2) + 8 = 6 * 2 + 8 = 20