10. Solve any three of the following differential equations. a) (3y-7x+7)dx + (7y-3x+3)dy = 0 b) cos x dy = y(sin x - y)dx c) p -py+x=0; where p d) (D 3D+2)y = x+x = dy dx 11. Find the changed form of the equation 3x + 3y + 2xy = 2 when the axes are turned through 45 the origin remaining fixed. 12. The line x+y=0 is a directrix of an ellipse, the point (2,2) is the corresponding focus. If the eccentricity be 1/3, find the equation of the other directrix. 13. Find the equation of the hyperbola in the standard form