The teacher will be very surprised to see your correct solution 😉
12 10 8 6 4 2 5*x - 12*x - 5*x - 8*x + 7*x - 12*x - 1 = 0
x1 = -0.436618744588831 - 0.957321364322621*i
x2 = 0.281676227588502*i
x3 = -0.436618744588831 + 0.957321364322621*i
x4 = 0.821911078567172 + 0.40634966545203*i
x5 = -0.281676227588502*i
x6 = 0.821911078567172 - 0.40634966545203*i
x7 = -0.821911078567172 + 0.40634966545203*i
x8 = 1.70591983668516
x9 = 0.436618744588831 - 0.957321364322621*i
x10 = -0.821911078567172 - 0.40634966545203*i
x11 = -1.70591983668516
x12 = 0.436618744588831 + 0.957321364322621*i
x12 = 0.436618744588831 + 0.957321364322621*i