Jawaban:

a. - 4 ≤ f(x) ≤ 5

b. - 4 ≤ f(x) ≤ 0

Penjelasan dengan langkah-langkah:

a. f(x) = (x + 1)(x - 3) = x² - 2x - 3

f ' (x) = 0

2x -2 = 0

x = 1 krn nilai x ini masuk interval,

masukkan nilai ujung² interval ke dalam f(x)

f(1) = (1+1) (1-3) = - 4 --> nilai min

f(-2) = (-2+1) (-2-3) = 5

f(4) = (4+1) (4-3) = 5 --> nilai max

-4 ≤ f(x) ≤ 5

b. f(x) = x³ - 3x²

f ' (x) = 0

3x² - 6x = 0

3x (x - 2) = 0

x = 0 x = 2 krn nilai x ini masuk interval, maka

masukkan nilai ujung² interval ke dalam f(x)

f(0) = 0³ - 3(0)² = 0 --> nilai max

f(-1) = (-1)³ - 3(-1)² = -1 - 3 = - 4

f(2) = (2)³ - 3(2)² = 8 - 12 = - 4 --> nilai min

- 4 ≤ f(x) ≤ 0