Question

Suatu fungsi dinyatakan dengan rumus f(x) = ax + b, jika f(3) = 5 dan f(-1) = -3. Maka nilai f(4) adalah ....

Answer 1

F (3) = 3a + b = 5
f (-1) = -a +b = -3
___________________ -
4a = 8
a = 2

3a +b = 5
3.2 + b = 5
b = 5-6
b= -1

f (4) = 4a + b = 8-1 = 7

Answer 2

F(x) = ax+b
f(3) = 3a+b = 5
f(-1) =-a+b =-3
__________ -
4a = 8 ----> a = 2
maka 3a+b = 5
3.2+b = 5
6+b = 5 -----> b = -1
didapat rumus fungsi :
f(x) = 2x-1
jadi, nilai f(4) = 2.4-1 = 8-1 = 7