diketahui fungsi f(x)=ax+b.jika f(-4)=6 dan f(6)= -4.maka tentukan nilai a dan b dan nilai f(2)

Jawab :

1) f(x) = ax + b
f(-4) = a(-4) + b
       = -4a + b = 6

f(x) = ax + b
f(6) = a(6) + b
      = 6a + b = -4

-4a + b = 6
6a + b = -4
__________ - 
-10a    = 10
a  =-10/10 
a = -1 ⇒ nilai A

6a + b = -4
6(-1) + b = -4
-6 + b = -4
b = -4 + 6
b = 2 ⇒ nilai B

a = -1
b = 2
f(x) = ax + b 
      = -1x + 2
f(x) = -x + 2

2) f(x) = -x + 2
f(2) = -2 + 2
f(x) = 0

f(x) = ax + b

f(-4) = 6
a . (-4) + b = 6
-4a + b = 6 ....................(1)

f(6) = -4
a . 6 + b = -4
6a + b = -4 ....................(2)

(1) dan (2) dieliminasi
-4a + b = 6
6a + b = -4
----------------- --
-10a = 10
a = 10/(-10)
a = -1

a = -1 disubtitusikan ke 6a + b = -4
6a + b = -4
6 . (-1) + b = -4
-6 + b = -4
b = -4 + 6
b = 2

f(x) = ax + b
f(x) = a . (-1) + 2
f(x) = -x + 2

f(2) = -x + 2
f(2) = -1 . 2 + 2
f(2) = -2 + 2
f(2) = 0

Jadi f(2) = 0

Moga membantu....