Question 4 [15] Write Octave commands for each of the following questions: a) Generate a vector x such that x(n) = 15e-"sin (0.31n) where n=0,1,2,3,4, ...,8. [2] b) Find ALL the roots of the following quadratic equation. 2x2 + 6x + 3 = 0 Hint: the root(s) of a quadratic equation, ax2 + bx+c = 0 is/are, -b + vb2 + 4ac X = 2a [5] c) By using while loop, calculate the factorial of n, n! = n(n 1)(n 2) ..... (1) The value n is your last digit of the student ID. number, i.e., (See Table 1 below) n Last digit of student ID. number 0 9 1 8 2 7 3 6 4 5 5 9 6 8 7 7 8 6 9 5 Table 1. Conversion table of last digit of student ID and n For example, if your student ID. is xxxxxxx8, then n! = 6! = 6(5)(4)(3)(2)(1) = 720 [8] 8