中四數學題(英文)

a) Find the possible value(s) of m.
Since the straight line y=mx+2 touches the parabola , so
y = mx+2 = x^2 - x + 6 have double root of x
x^2 - (m+1)x + 4 = 0......(1)
△ = (m+1)^2 - 4*4 = 0
(m+1)^2 = 16
m+1 = 4 or m+1 = -4
m = 3 or m = - 5
b)When m = - 5 , sub it to (1):
x^2 - (-5+1)x + 4 = 0
x^2 + 4x + 4 = 0
(x + 2)^2 = 0
x = - 2
y = mx+2 = (-5)(-2) + 2 = 12
The coordinates is ( - 2 , 12 )