fungsi h(x) = ax + b . jika h(1) = -5 dan h(7) = 7 . nilai h(3) adalah..?

Kelas 8 Matematika
Bab Fungsi

h(x) = ax + b

h(1) =   a + b = -5
h(7) = 7a + b = 7
         ------------------ -
                -6a = -12
                   a = 2

a + b = -5
2 + b = -5
b = -5 - 2
b = -7

h(x) = 2x - 7
h)3) = 2 . 3 - 7
h(3) = -1

H(1)=a(1)+b
-5=a+b.....(1)

h(7)=a(7)+b
7=7a+b.....(2)

eleminasi pers. 1&2
a+b=-5
7a+b=7
------------ -
6a=12
a=2

substitusi kan ke pers. 1
a+b=-5
2+b=-5
b=-7

h(3)=3a+b
=3(2)+(-7)
=6+(-7)
=-1