x + y = 2, x2 + y2 = 4 হলে x3 + y3 = কত?

x + y = 2, x² + y² = 4 হলে x³ + y³ = কত?

A 8

B 9

C 16

D 25

Correct Answer: Option A

দেওয়া আছে,
x + y = 2, x² + y² = 4

x² + y² = (x + y)² - 2xy
বা, 4 = (2)² - 2xy
বা, 4 = 4 - 2xy
∴ xy = 0

এখন,
x³ + y³ = (x + y)³ - 3xy(x + y)
= (2)³ - 3×0×2
= 8