Q2*) Consider the extremisation of the integral I[y] = √²² F(x,y,y', y") dx x1 when y and y' are prescribed only at x = x1. Derive the so-called 'natural boundary conditions' that must be satisfied at x = x2. Taking a specific example: The functional I [y] is defined by I[y] = √² ((y″)² + y) dx with y(0) = 0 and y'(0) = 0. Write down the fourth-order Euler-Lagrange equation for this problem, stating the four boundary conditions. Find the general solution of the Euler-Lagrange equation, and then impose the boundary conditions to find the extremal.

3 00 By changing to circular coordinates, evaluate foo √²²+v³ dx dy.

3. Z e2 n dz, n = 1, 2,. ..

Q/ By using polar Coordinates show that the system below has a limit cycle and show the stability of + his limit cycle: X² = x + x(x² + y² -1) y* = −x + y (x² + y²-1) -x

xy Q/Given H (X,Y) = ex-XX+1 be a first integral find the corresponding system and study the Stability of of critical point of this system.

Q/ show that H (X,Y) = x²-4x-x² is 2 first integral of the system Y° = y 0 y° = 2x + x 3 then study the stability of critical point and draw phase portrait.

Q/Given the function H (X,Y) = H (X,Y) = y 2 X2 2 2 ²** 3 as a first integral, find the correspoding for this function and draw the phase portrait-

Q/ show that the system has alimit cycle and draw phase portrait x = y + x ( 2-x²-y²)/(x² + y²) ½ 2 y = -x+y ( 2-x² - y²) / (x² + y²) ½/2

A sequence X = (xn) is said to be a contractive sequence if there is a constant 0 < C < 1 so that for all n = N. - |Xn+1 − xn| ≤ C|Xn — Xn−1| -