已知向量m(根号3,1）,向量n是与向量m夹角为60°的单位向量

(1)
m =(√3,1)
let n be (x,y )
|n| =1
=> x^2+y^2=1
m.n = |m||n|cos60°
(√3,1).(x,y) = 2(1/2)
√3x+ y = 1
y = 1-√3x
x^2+y^2=1
x^2 + 3x^2 -2√3x +1 = 1
2x(2x-√3) =0
x=0 or x = √3/2
when x= 0 y= 1
when x=√3/2,y= -1/2
n = (0,1) or (√3/2,-1/2)
(2)
for n=(0,1),n与Q不能共线
ie n= (√3/2,-1/2)
p=(√3x^2,x-y^2)
n与p垂直 =>
n.p =0
(√3/2,-1/2).(√3x^2,x-y^2)=0
3x^2 -x + y^2 =0
t = y^2 + 5x +4
= (-3x^2+x) +5x +4
= -3x^2+6x +4
t' = -6x+6 =0
x= 1
t''=-6