7. Determine the longest interval in which the given initial value problem is certain to have a unique twice differentiable solution. Do not attempt to find the solution. (i) (t-1)y" - 3ty' + 4y = sint, y(-2) = 2, y'(-2) = 1 (ii) t(t-4)y" + 3ty + 4y = 2, y(3) = 0, y'(3) = -1 (iii) (x - 2)y" + y + (x 2)(tan x)y = 0, y(3) = 1, y'(3) = 2. 8. Find the Wronskian of the given pair of functions: (i) cost, sint (ii) 0,et sint (iii) x, (iv) cos0, 1+cos 20. Ie