dik rumus fungsi f(x)=ax+b jika f(1)=4 dan f(3)=14, maka nilai f(-2) adalah

f(x) = ax + b
f(1) = a + b = 4
f(3) = 3a + b = 14
--------------------------(-)
- 2a = - 10
a = 5
a + b = 4
5 + b = 4
b = 4 - 5
b = - 1
f(x) = 5x - 1
f(-2) = 5(-2) - 1 = - 10 - 1 = - 11