Use MATLAB to plot the polynomials y = 3x⁴ - 6x³ + 8x² + 4x + 90 and z = 3x³ + 5x² - 8x + 70 over the interval -3 ≤ x ≤ 3. Properly label the plot and each curve. The variables y and z represent current in milliamperes; the variable x represents voltage in volts.