A special solution of differential equation y '' + 2Y '+ y = x ^ 2 + 1 is obtained

A special solution of differential equation y '' + 2Y '+ y = x ^ 2 + 1 is obtained

Let the special solution y * = ax & # 178; + BX + C, then y * '= 2aX + B, y * "= 2A, and substitute it into the original equation to obtain 2A + 2 (2aX + b) + (AX & # 178; + BX + C) = x & # 178; + 1, that is, ax & # 178; + (4a + b) x + (2a + 2B + C) = x & # 178; + 1. A = 1, B = - 4, C = 7, so the special solution y * = x & # 178; - 4X + 7