※ 引述《partialydx (蒸籠中的阿飛)》之銘言：
: (a)show that cos(X^2)>= cosx for 0 <= X <=1
0 <= x^2 <= x <= 1 < π/2
=> cos(x^2) >= cos(x)
: (b)deduce that π/6
: ∫ cos(X^2) >= 0.5
: 0
π/6
∫ cos(x^2) dx
0
π/6
>= ∫ cos(x) dx
0
= sin(π/6)
= 1/2 = 0.5
: 如果是多項式型的,譬如1<=根號1+X^3<=1+X^3
: 我還知道
: 可是這種的不知從何下手....