Parabola y2 = 4x, slope - 2 straight line intersection parabola at a, B two points, find a, B two points distance

Parabola y2 = 4x, slope - 2 straight line intersection parabola at a, B two points, find a, B two points distance

Let a (x1, Y1) B (X2, Y2) linear equation y = - 2x + B Y1 ^ 2 = 4x1 (1) Y2 ^ 2 = 4x2 (2) as a difference, the deformation is: (y1-y2) / (x1-x2) = 4 / (Y1 + Y2) = - 2, Y1 + y2 = - 2, y = - 2x + B, y ^ 2 = 4x together, we get: 4x ^ 2-8x + B ^ 2 = 0, X1 + x2 = 2, Y1 = - 2x1 + B, y2 = - 2x2 + B