diketahui fungsi f(x)=axb.jika f(-1)=21 dan f(1)=29,maka nilai f(-5) adalah....

-1a + b = 21
1a + b = 29 dieliminasi

-2a + 0 = -8
a  = -8 / -2 = 4
b=-1(a) + b = 21
   = -1.4 + b = 21
   = -4 + b = 21
   b = 21+4 = 25
 f(x) = 4x + 25
 f(-5) = -20 + 25 = 5

tolong jadikan jawbaan terbaik yaa 
    

maksudnya f
(x) = ax + b
maka,
-1a + b = 21 { | }
1a + b = 29 { || }
________ -
-2a = -8
a = 4
{ | } ke { ||| }
-1a + b = 21
-1 . 4 + b = 21
-4 + b = 21
b = 21 + 4
b = 25

Rumus F
f(x) = 4x + 25
f(-5) = 4 . -5 + 25
f (-5) = -20 + 25
f(-5) = -5