8.k = 2 (1/2) or-1 ≤ k < 1.

9. Forget the formula and don't do it.

10. The included angle between the vector m and the X axis is 30 (coordinate x/y = 3 (1/2)).

If the angle between vector n and m is 60, then the angle between vector n and x axis is 90 or -30.

Therefore, the vector n is (0, 1) or (3 (1/2),-1).

Because of the lines of vector N and q***, vector N is (3 (1/2),-1).

The vector n is perpendicular to p, so 3 (1/2) × 3 (1/2) x2+(-1) × (x-y2) = 0.

3x^2-x+y^2=0 y^2=x-3x^2

t=y^2+5x+4=-3x^2+6x+4=-3(x- 1)^2+7

When x= 1, the maximum value of t is 7.

1 1. Because of tangency, the radius is that the distance from point O to a straight line is 2 (using the distance formula from point to straight line).

The equation of a circle is x 2+y 2 = 4.

Second, ask others, I won't.