駭客數學p1-28

[gncpkat]

設g(x)為一線型函數，滿足3g(2)<=2g(3),5g(4)>=4g(5),且g(5)=5,則g(2)=?
(A)2 (B)3 (C)4 (D) 5
答案：(A)

[dream10]

令g(x)=ax+b
將上式代入3g(2)<=2g(3) =>b<=0
將上式代入5g(4)>=4g(5) =>b>=0
所以b=0
g(5)=5=>a=1
g(2)=2

[gncpkat]

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