要步驟+答案 thx~
1.假設 f (x) = (24/x+3) - x 是一個函數。
a.找出f (x)的定義域。
b.求下列各題的值:
(i) f (3)
(ii) f (5)
(iii) f (15)
c. f (3) * f (5) = f (15) 是否正確?
2. 已知f (x) = k x - 2。若f (2) = 4 ,求k的值。
3.若S (x) = 3 k x + k 及 S (8) = 5
a. 求k的值。
b. 求a的值 ,使S (a) = -7
中4數學 函數
2010-01-13 3:11 am
回答 (2)
2010-01-13 4:39 am
✔ 最佳答案
a) 唔識中文=.=b) i) f(3) = [24/(3) + 3] - (3)
= 1
f(5) = [24/(5) + 3] - (5)
= -2
f(15) = [24/(15) + 3] - (15)
= -41/3
c) f(3) * f(5)
= 1 * -2
= -2
=/= f(15)
2. f(x) = kx - 2
f(2) = k(2) - 2
4 = 2k - 2
k = 3
3.a. S(x) = 3kx + k
S(8) = 3k(8) + k
5 = 25k
k = 1/5
b. S(x) = 3kx + k
S(a) = (3a/5) + (1/5)
-35 = 3a + 1
-36 = 3a
a = -12
參考: me
2010-01-13 4:18 am
1. f (x) = 24/(x+3) - x
a. f (x)的定義域是除了-3外的所有實數
b. (i) f (3) = 24/(3+3) - 3 = 1
(ii) f(5) = 24/(5+3) - 5 = -2
(iii) f(15) = 24/(15+3) - 15 = 24/18 - 15 = -41/3
c. f (3) * f (5) = f (15) 並不正確
2. f(x) = k x - 2
f(2) = 2k - 2 = 4
2k = 6
k = 3
3. S(x) = 3 k x + k 及 S (8) = 5
a. S(8) = 3k*8 + k = 5
24k + k = 5
k = 5/25 = 0.2 => S(x) = 0.6x + 0.2
b. S(a) = -7
0.6a + 0.2 = -7
0.6a = -7.2
a = -12
a. f (x)的定義域是除了-3外的所有實數
b. (i) f (3) = 24/(3+3) - 3 = 1
(ii) f(5) = 24/(5+3) - 5 = -2
(iii) f(15) = 24/(15+3) - 15 = 24/18 - 15 = -41/3
c. f (3) * f (5) = f (15) 並不正確
2. f(x) = k x - 2
f(2) = 2k - 2 = 4
2k = 6
k = 3
3. S(x) = 3 k x + k 及 S (8) = 5
a. S(8) = 3k*8 + k = 5
24k + k = 5
k = 5/25 = 0.2 => S(x) = 0.6x + 0.2
b. S(a) = -7
0.6a + 0.2 = -7
0.6a = -7.2
a = -12
收錄日期: 2021-04-23 23:23:45
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