If x - y = 4 and xy = 3, then what is the value of x3 - y3?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 100.
x - y = 4
⇒ x2 - 2xy + y2 = 16
⇒ x2 + xy + y2 = 16 + (3 × 3)
⇒ x2 + xy + y2 = 25
⇒ (x - y) (x2 + xy + y2) = 25 × 4
⇒ (x - y) (x2 + xy + y2) = 100
⇒ x3 - y3 = 100
The value of x3 - y3 is 100.