This is in Differential Calculus. This is only multiple choice. Provide necessary solution for each items. Thank you and Godbless.

16. Find y" in the parametric equations x = cos* 0, y = 2 sin* 9. A) sec 0 C) sin sec$6 B) sec Atan e D) cos e 17. Given = =x y + 5xy -2x + 3y , what is :, ? A) x' + 10ry + 9y C) 2xy + 5y' -6x B) 2ry + 5ry' + 9y D) 2r+ 5y-6x 18. The temperature / in degrees centigrade at each point (x, y) in the region x + y s I is given by I'= 16x + 24x + 40y . Find the temperature at the coldest point in the region. A) -5"C C) -9C B) -12'C D) -10"C