Question

If a + b = 8 and ab = 15 then find the value of {a³ + b³}

• A. 260
• B. 152
• C. 124
• D. 98

Answer 1

Answer:

B. 152

1. Identify the given values: You are given a + b = 8 and ab = 15.

2. Apply the derived identity: Substitute these values into the formula a³ + b³ = (a + b)((a + b)² - 3ab).

3. Perform the substitution: a³ + b³ = (8)((8)² - 3 * 15)

4. Calculate the square and product:a³ + b³ = (8)(64 - 45)

5. Perform the subtraction inside the parenthesis:a³ + b³ = (8)(19)

6. Calculate the final product:a³ + b³ = 152