marks A student was asked to find the first derivative - of the function: dx cosh x - 2x2 y = cos 3x Their solution is below. Find the mistakes that this student made in each line and correct them, explaining what they did wrong. Show what the final correct solution should be. student's solution: dy Line 1 (cosh x - 2x2) (3 sin 3x) - (cos 3x) (sinh x - 4x) dx (cos 3x) 2 3 sin 3x cosh x - 2x2 sin 3x - cos 3x sinh x + 4x cos 3x Line 2 = (cos 3x)2 Line 3 3 sin 3x cosh x - 2x2 sin 3x - sinh x + 4x = cos 3x