Question

Suatu fungsi dirumuskan f(x)=ax+b. jika f(-1)=9 dan f(3)=-7, maka nilai f(-4) adalah ,,,,pakai cara okay,,,thank you??

Answer 1

F(x) = ax + b

pers 1
f(-1) = -1a + b
9 = -a + b

pers 2
f(3) = 3a + b
-7 = 3a + b

seliminasikan pers 2 dg pers 1
-7 = 3a + b
9  = -a  + b  -
-16 = 4a 
a = -16/4
a = -4

cari b

 
9 = -a + b
9 = -(-4) + b
9 = 4 + b
b = 9-4
b = 5

sehingga f(-4) adalah
f(-4) = -4a + b
f(-4) = -4(-4) + 5
f(-4) = 16 + 5
f(-4) = 21