It is known that the equation of parabola is y quadratic = 4x, the straight line I passes through the fixed point P (- 2.1), and the slope is K It is known that the equation of parabola is y quadratic = 4x, the straight line I passes through the fixed point P (- 2.1), and the slope is K. when the value of K is, the straight line and parabola have only one common point and two common points

Let L: Y-1 = K (x + 2) (from image, K exists)
So y ^ 2 = 4x, Y-1 = K (x + 2) simultaneous: K ^ 2x ^ 2 + (4K ^ 2 + 2k-4) x + (2k + 1) ^ 2 = 0
If there is a common point: △ = 0, then k = 1 / 2 or - 1
There are two common points: △ 0 is: - 1

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