Mohin bantuannya ya. Tolong dijawab butuh banget.?????

Dik. f(x) = ax + b, f(3) = 15 & f(5) = 20.
Dit. a) Nilai a & b
b) Bentuk fungsinya?
c) f(-2) ?

Jawab...

f(x) = ax + b

f(3) = 3a + b = 15
f(5) = 5a + b = 20
      ---------------------- (-)
@ -2a = -5
@ a = 2,5

b : 
3a + b = 15
3(2,5) + b = 15
7,5 + b = 15
b = 15 - 7,5
b = 7,b

#B

f(x) = ax + b
f(x) = 2,5x + 7,5

#C
f(-2) = 2,5 (-2) + 7,5
f(-2) = -5 + 7,5
f(-2) = 2,5

Semoga membantu... ^_^