diketahui g(x)=ax+b jika g=(1)=-7dan(-3)=1 tentukan nilai g(2)

Bab Fungsi
Matematika SMP Kelas VIII

g(x) = ax + b

g (1) =    a + b = -7
g(-3) = -3a + b = 1
         ------------------- -
                  4a = -8
                    a = -2

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

g(x) = -2x - 5

g(2) = -2 . 2 - 5
       = -4 - 5
       = -9

g(1)=-7
a(1)+b=-7
a+b=-7........(1)

g(-3)=1
a(-3)+b=1
-3a+b=1......(2)

maka eliminasi persamaan (1) dan (2)
a+b=-7
-3a+b=1
_______-
4a=-8
a=-8/4=-2

substitusi a
a+b=-7
(-2)+b=-7
b=-7+2
b=-5

maka g(x)=-2x-5
g(2)=-2(2)-5
=-4-5=-9