Show that the solution of differential equation :

If x changes from 4 to 4·01, then find the approximate change in log x.
For the curve y = 5x – 2x³, if x increases at the rate of 2 units/sec, then find the rate of change of the slope of the curve when x = 3.
The position vectors of points A, B and C are , and respectively. If C divides the line segment joining A and B in the ratio 3 : 1, find the values of λ and μ.