20/01/16 20:48:24.09 9JmmA2mq.net
一枚目
yは単調増加
f(1) = a+b+1 > 1 (← a>0,b>0)
f(2) = 8a+4b+1 ≦ 2
I = [ (a/4)x^4 + (b/3)x^3 +x ](x=1,2)
= (15/4)a + (7/3)b + 1
>1,
I = 19/12 - (7/12)(1-8a-4b) -(11/12)a ≦ 19/12,
二枚目
yは単調減少
f(a) = -2a+b = -3,
f(7) = -14+b = -9,
より (a,b) = (4,5)