Diketahui rumus suatu fungsi f(x)=ax+b, f(3)=5, dan f(-1)= -3. nilai f4 adalah...

MAPEL = MATEMATIKA
KELAS = 8
BAB = RELASI & FUNGSI

diketahui :
rumus fungsi ➡ f(x) = ax + b
f(3) = 5
f(-1) = -3

ditanya : f(4) ??

f(3) = ax + b
➡ 3a + b = 5..........( 1 )

f(-1) = ax + b
➡ -a + b = -3............( 3 )

eliminasi nilai b pada pers. ( 1 ) dan ( 2)
3a + b = 5
-a + b = -3
_________-
4a = 8
a = 8/4
a = 2

subtitusi nilai a = 2 pada pers. ( 1 )
3a + b = 5
3(2) + b = 5
b = 5 - 6
b = -1

rumus fungsi :
➡ f(x) = ax + b
➡ f(x) = 2x - 1

f(4) = 2x - 1
f(4) = 2(4) - 1
f(4) = 8 - 1
f(4) = 7

semoga membantu