"FIND GENERAL SOLUTION OF 18, 19 AND 23 ONLY.
18. xy' = 2y + x³ cos x 19. y' + y cotx = cos x 20. y'= 1 + x + y + xy, y(0) = 0 21. xy' = 3y + x4 cos x, y(2л) = 0 22. y' = 2xy + 3x² exp(x²), y(0) = 5 23. xy' + (2x − 3) y = 4x4"