-3: y = -2 * (-3) - 7 = 6 - 7 = -1
0: y = -2 * 0 - 7 = -7
3: y = -2 * 3 - 7 = -6 - 7 = -13
6: y = -2 * 6 - 7 = -12 - 7 = =-19
