3. (a) Show using the complex potential or velocity, that a doublet can be generated by a pair of equal-strength opposite-signed point vortices, brought infinitely close together, while holding the product of their strength and the distance between them constant. Give the doublet strength of this product, and determine the doublet direction as compared to the initial position of the vortices. (b) Explain the multivaluedness of the function loge(z). What about loge(z-A), where A is a complex constant?