✨ 最佳解答 ✨
有正解嗎? 26/8 ?
【a^b = a 的 b 次方】看不懂我再手寫
y = f(x) = ax + b
f(3^8) = 2, f(3^10) = 7
f(3^8) = 3^8 a + b = 2 ...(1)
f(3^10) = 3^10 a + b = 7 ...(2)
(2)-(1)
(3^10 - 3^8) a = 5
3^8(3^2 - 1) a = 5
3^8 a = 5/8 算到這邊就好,後面用的到
代入 (1)
5/8 + b = 2, b = 11/8
f(3^9) = 3^9 a + b
= (3 * 3^8) a + b
= 3 * (3^8 a) + b
= 3 * 5/8 + 11/8
= 26/8 = 13/4
很清楚,非常謝謝你!
正解是13/4沒錯(約分後的