Question 1 25 pts Calculate the total differential of z = x2y + xy2 + 5x2 - 8xy - y2 - 41x + 15y + 76. O (2xy+ y + 10x - 8y - 41) dx + (x2 + 2xy - 8x - 2y+ 15) dy O (2x + 2y - 8) dz O (-2x - 2y + 8) dz O ( x2 + 2xy - 8x - 2y + 15) dx + (2xy + 12 + 10x - 8y - 41)dy Question 2 25 pts Estimate the value of 1954.81 + 1528.81 by using differentials with regard to the function f(x, y) = Vx2 + 12. Hint: 954.81 = (30 + 0.9)2 and 1528.81 = (40 - 0.9). O 49.81 O 49.84 O 49.82 O 49.83Question 3 25 pts If the total differential of a function is zero, then the function is constant. 0 True 0 False Question 4 25 pts The second partial derivatives of a function must be calculated in order to determine the total differential of the function. 0 True 0 False