he truc xoy; { AB,oy; AC,ox)
K(1;8)
∆ qua K : y =ax-a +8 (a<0)
M giao ∆ oy M(0; 8-a8
N giao ox N(a-8)/a;0)
MN^2=(8-a)^2+(1-8/a)^2
a^2-16a+64+1-16/a+64/a^2
[a^2+(8/a)^2]-16(a+8/a)+65
[(a+8/a)]^2-16(a+8/a)+64-15
a+8/a=t; ≤-4√2
(t-8)^2-15≥(4√2+8)^2-15

min MN=√(21+48√2)

giai thich ro hon dk khong
kho hieu qua

lam sai tu dong thu 8 roi le huy oi

sai cai gi the ?

16(a+8/a)

Dat 16 ra roi. Trong ngoac sao con 8

ok