If a (1,2) is outside the parabola y ^ 2 = 2x, P moves on the parabola Find the maximum value of | PA | - | Pb |

If a (1,2) is outside the parabola y ^ 2 = 2x, P moves on the parabola Find the maximum value of | PA | - | Pb |

Make Aa1 ⊥ alignment L through a to A1,
The equation of Quasilinear L is x = - 1 / 2
If Aa1 and parabola intersect at P, then | PA1 | = | PF|
Point P makes | PA | - | Pb | - maximum = | Aa1 | = 1 - (- 1 / 2) = 3 / 2