唔知點做..天日交

y=mx的圖像與y=x^2-2x+4的圖像只相交一點p
(a)求m的值
(b)利用從(a)所得的值,求p的坐標
(a)
令
y=x^2-2x+4=mx
x^2-2x+4=mx
x^2-(2+m)x+4=0
因只相交一點p
判別式是0
(2+m)^2-16=0
2+m=4 or 2+m=-4
m=2 or m=-6
(b)
當m=2
x^2-(2+m)x+4=0
x^2-4x+4=0
(x-2)^2=0
x=2
y=mx=2*2=4
當m=-6
x^2-(2+m)x+4=0
x^2+4x+4=0
(x+2)^2=0
x=-2
y=mx=-6*-2=12
p的坐標是(2,4) 或(-2,12)