Please answer the following using Matlab. ??????? Problem 1: Define \( a=2, b=5, c=-3 \) in Octave, then use Octave to evaluate the following expressions: a) \( \frac{1}{2} a^{3}-\frac{(a-b)^{2}}{a-b c+4 b}+\frac{4}{5} c \) b) \( \cos (a \pi)+\frac{b 1 answer