fungsi(x)=ax+b jika f(-2)=19 dan f(4)=-11 maka nilai f(-3) adalah

cara cepat

-3 , -2 , 4
jarak -3 ke -2 = 1
jarak -2 ke 4 = 6

... , 19 , - 11
jarak ... ke 19 = x
jarak 19 ke - 11 = -30

jarak x = -30 : 6 = - 5 X 1 = -5

.../ f(-3) = 19 -(-5)
= 24

f(x) = ax + b
f(-2)= -2a + b = 19
f(4) = 4a + b = -11 _
-6a = 30
a = 30 / -6
a = -5
-2a + b = 19
-2 × (-5) + b = 19
10 + b = 19
b = 19 - 10
b = 9
f(x) = ax + b
f(x) = -5x + 9
f(-3) = -5 × (-3) + 9
= 15 + 9
= 24