Question

Fungsi f didefinisikan dengan rumus f(x)= ax + b. jika f(-3)=15 dan f(-2)= 0 , nilai f(-5) adalah
a. -21
b.-18
c18
d.21

Answer 1

F(-3)=-3a+b=15 f(-2)=-2a+b=0 (-3a+b)-(-2a+b)=15-0 -a=15 a=-15 f(-2)=30+b=0 b=0-30=-30

Answer 2

Diket;

f(x)= ax + b
f(-3)=15
f(-2)= 0
f(-5) ?

jawab;

f(-3)=15
15 = -3a + b ...(1)
f(-2)= 0
0 = -2a + b ...(2)

eliminasi, didapat :
-3a + b = 15
-2a + b = 0
__________-
-a = 15
a = -15

-2a + b = 0
30 + b = 0
b = -30

Nilai f(-5) ??
f(-5) = -5a + b
f(-5) = -5(-15) - 30
f(-5) = 72 - 30
f(-5) = 42

sebenarnya masih ada cara lain antara lain;subsitusi