22.Suatu fungsi dirumuskan f(x) = 7x - 1,jika f(a) = 48 f(b) = -22 maka nilai a + b adalah ... a.-4. c.7 b. 4. d.9 23.Diketahui rumus fungsi a

22. f(x) = 7x - 1
f(a) = 7a - 1
48 = 7a - 1
48 + 1 = 7a
49 = 7a
a = 49/7
a = 7

f(b) = 7b -1
-22 = 7b - 1
-22 + 1 = 7b
-21 = 7b
b = -21/7
b = -3

a + b = 7 + (-3) = b.4


23. f(2x+ 1) = 4x+5
f(2) = ...
Pertama, kita harus mencari berapa nilai x :
2 = 2x + 1
2 - 1 = 2x
1 = 2x
x = 1/2

Maka f(2) = 4 × 1/2 + 5
= 4/2 + 5
= 2 + 5
= c. 7