The tangent equation of the curve y = X3 + X parallel to the straight line y = 4x-1 is () A. 4x-y = 0b. 4x-y + 2 = 0 or 4x-y-2 = 0C. 4x-y-2 = 0d. 4x-y = 0 or 4x-y-4 = 0

The tangent equation of the curve y = X3 + X parallel to the straight line y = 4x-1 is () A. 4x-y = 0b. 4x-y + 2 = 0 or 4x-y-2 = 0C. 4x-y-2 = 0d. 4x-y = 0 or 4x-y-4 = 0

Let y ′ = 4 {x2 = 1} x = ± 1. Substitute x = 1 into y = X3 + X to get y = 2. So the tangent equation is Y-2 = 4 (x-1) {4x-y-2 = 0; substitute x = - 1 into y = X3 + X to get y = - 2, so the tangent equation is y + 2 = 4 (x + 1)} 4x-y + 2 = 0