108 全國聯招
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Re: 108 全國聯招
計算第 3 題
(1) 0 ≦ x ≦ π
0 ≦ 2x ≦ 2π
cos(2x) = cos(x) * [sin(x) + sin(x)] = sin(2x)
2x = π/4 or (5/4)π
x = π/8 or (5/8)π
(2) π < x < 2π
2π < 2x < 4π
cos(2x) = cos(x) * [sin(x) - sin(x)] = 0
2x = (5/2)π or (7/2)π
x = (5/4)π or (7/4)π
(1) 0 ≦ x ≦ π
0 ≦ 2x ≦ 2π
cos(2x) = cos(x) * [sin(x) + sin(x)] = sin(2x)
2x = π/4 or (5/4)π
x = π/8 or (5/8)π
(2) π < x < 2π
2π < 2x < 4π
cos(2x) = cos(x) * [sin(x) - sin(x)] = 0
2x = (5/2)π or (7/2)π
x = (5/4)π or (7/4)π
Re: 108 全國聯招
選擇第 7 題
設所花費時間的期望值為 E(X)
則 E(X) = 0.6 * (5 + E(X)) + 0.2 * (5 + E(X)) + 0.2 * 10
解 E(X)
設所花費時間的期望值為 E(X)
則 E(X) = 0.6 * (5 + E(X)) + 0.2 * (5 + E(X)) + 0.2 * 10
解 E(X)