Jawaban:

Penyelesaian :

f(x) = ax + b jika f(2) = 5 dan f(-1) = -1 maka tentukan

• 1 nilai a
• 2 nilai b
• 3 rumus fungsi
• 4 f(3)

1. Mencari nilai a

f(x) = ax + b

f(2) = a(2) + b = 5

2a + b = 5

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

-a + b = -1

2a + b = 5

-a + b = -1 -

3a = 6

a = 6/3

a = 2

2. Mencari nilai b

Substitusi nilai a ke pers (1)

2a + b = 5

2(2) + b = 5

4 + b = 5

b = 5 - 4

b = 1

3. Rumus fungsi

f(x) = ax + b

f(x) = 2x + 1

4. Mencari f(3)

f(x) = ax + b

f(x) = 2x + 1

f(3) = 2(3) + 1

f(3) = 6 + 1

f(3) = 7