If a + b = 4, and ab = 3, then what is the value of a3 + b3 = ?

1. 9
2. 35
3. 28
4. 20

If a + b = 4, and ab = 3, then the value of a³+ b³ = 28

Given: a + b = 4, ab = 3

We know that,

(a + b)² = a² + b² + 2ab

(a³ + b³) = (a + b) (a² + b² - ab)

By using this

(a + b)² = a² + b² + 2ab

By substituting

⇒ (4)² = a² + b² + 2 × 3

⇒ a² + b² = 10 … (1)

⇒ (a³ + b³) = (4) × (10 - 3)

⇒ (a³ + b³) = 28

Therefore, the required result will be 28.