In Exercises, three solutions of the equation y = ax2 + bx + c are given. Use a system of three equations in three variables and Gaussian elimination or Gauss-Jordan elimination to find the constants a, b, and c and write the equation.
a. (-3, 12), (-1, -7), and (1, -2)
b. (-1, 0), (1, -3), and (3, -22)