Question

diketahui f(x) = ax + b. Jika f(2) = 4, dan f(5) = 13, maka nilai f(8) - f(3)...

a. 7
b. 9
c. 15
d. 22
Tolong dengan Jalannya yaa..

Answer 1

Jawab:

f(2) = 4

a(2) + b = 4

2a + b = 4      (i)

f(5) = 13

a(5) + b = 4

5a + b = 4      (ii)

(ii) 5a + b = 13

(i)  2a + b = 4 -

    3a       = 9

    a = 3

2(3) + b = 4

6 + b = 4

b = 4-6

b = -2

f(x) = 3x - 2

f(8) - f(3) = ( 3(8) - 2 ) - ( 3(3) - 2 )

f(8) - f(3) = ( 24 - 2 ) - ( 9 - 2 )
f(8) - f(3) = 22 - 7

f(8) - f(3) = 15 (C)