Question

Fungsi f ditentukan dengan rumus f(x) = ax +b. Bila f(4) = 2 dan f(6) = 9, maka nilai 3a-2b adalah....

Answer 1

F(4) = 4a+b=2
F(6)= 6a+b=9
..................... _
A= 7/2
4a+b=2
4(7/2) + b = 2
14 +b =2
B= - 12
Maka nilai 3a - 2b = 3(7/2) - 2(-12) =10,5 +24 = 34,5

Answer 2

F(x) = ax + b
f(4) = 2 》a.4 + b = 2 => 4a + b = 2
f(6) = 9 》a.6 + b = 9 => 6a + b = 9

Eliminasi :
4a + b = 2
6a + b = 9
---------------- -
-2a + 0 = -7
-2a = -7
a = -7 : -2
a = 3,5

Subtitusi :
a = 3,5
4a + b = 2
4.3,5 + b = 2
14 + b = 2
b = 2 - 14
b = -12
jadi, nilai 3a - 2b
=> 3.3,5 - 2.-12
10,5 - (-12) => 10,5 + 24 = 34,5