To divide the polynomial x^3 + (1-k^2)x + k by (x+k) using synthetic division, the process involves setting up the synthetic division with -k as the divisor. The resulting synthetic division yields coefficients that simplify to x^2 - kx + 1. This shows that the polynomial can be expressed as x^3 + (1-k^2)x + k = (x+k)(x^2 - kx + 1). The method effectively demonstrates how to perform synthetic division with a linear binomial. Understanding this technique is crucial for polynomial division in algebra.