1.The first three terms of the expansion of (1+kx)^n are 1+6x+27x^2. Find k and n and hence find the term in x^3.

2.In the expansion of (1+ax)^n, in ascending powers of x, the coefficient of x is 12 and the coefficient of x^3 is six times the coefficient of x^2. Find a and n.

3.Find dy/dx in terms of x and y: 2sin2xcos3y=1

Could anyone help me with the above questions. Thanks