Fungsi f dirumuskan f(x) = px + q. Jika f(3) = 9 dan f(-6) = 3, maka rumus fungsi f(x) adalah

f(x) = px+q
f(3)= p(3)+q = 9
= 3p+q =9
f(-6)= p(-6)+ q= 3
=-6p+q= 3

3p+q = 9
-6p+q = 3
------------- -
9p = 6
p. = 6/9
p = 1/3

3p+q = 9
3(1/3)+q =9
q = 9

f(x) = px+q
= 1/3x+9