Ab = b-a = (-1;-1)-(3;5)=(-4;-6)
cd = d-c
d = cd + c = ab + c = (-4;-6)+(0;4) = (-4;-2)
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a(n+5;-8)||b(5;1-n)
вектора коллинеарны, если
a=k·b
k - скаляр
(n+5;-8)=k·(5;1-n)
n+5 = 5k
-8 = k-nk
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n = 5k-5
-8 = k - (5k-5)k
-8 = k-5k²+5k
5k²-6k-8 = 0
D=36+4*5*8=196
k₁ = 6/10-14/10 = -4/5
n₁ = 5*(-4/5)-5 = -4-5 = -9
k₂ = 6/10+14/10 = 20/10 = 2
n₂ = 5*2-5 = 5
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ответ
-9; 5