nilai dari f(30) adalah

Jawab :

f(x) = ax + b

(0,-1)
f(0) = -1
a.0 + b = -1
b = -1

(3,2)
f(3) = 2
3a + (-1) = 2
3a = 2 + 1
a = 1

f(x) = ax + b = x - 1

f(30) = 30 - 1
f(30) = 29