jika f(x)=ax+b,f(1)=2, dan f(2)=1 maka tentukan. b bentuk paling sederhana dari f(x-1)

f(x) = ax + b
f(1) = a(1) + b
2 = a + b

f(2) = a(2) + b
1 = 2a + b

2 = a + b
1 = 2a + b
________ -
1 = -a
a = -1

2 = a + b
2 = -1 + b
b = 2 + 1 = 3

f(x - 1) = (-1)(x - 1) + (3)
= -x + 1 + 3
= -x + 4