JUST NEED HELP WITH #2 PLEASE USING MATLAB

Plot the polynomial y = -0.4x^4 + 7x^2 - 20.5x - 28 in the domain -5 lessthanorequalto x lessthanorequalto 4. First create a vector for x, next use the polyval function to calculate y, and then use the plot function. Plot the polynomial y = -0.001x^4 + 0.051x^3 - 0.76x^2 + 3.8x - 1.4 in the domain 1 lessthanorequalto calculate y, and then use the plot function. Use MATLAB to carry out the following multiplication of two polynomials: (2x^2 + 3)(x^3 + 3.5x^2 + 5x - 16)