
y + 8x = x²  13
y = x²  8x  13
x²  8x  13 = 0
x² + 8x + 13 = 0 ← divided by 1
x² + 8x = 13 ← subtracted 13
x² + 8x + 16 = 13 + 16 ← took half of 8, squared, and added to each side
(x + 4)² = 3 ← factored left side
x + 4 = ±√3 ← took square root of each side
x = 4 ± √3 ← subtracted 4
 Proof
