中4數學 函數

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

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