x + y = 2, x2 + y2 = 4 হলে, x3 + y3- এর মান কত?
সমাধান
সঠিক উত্তর: Option C
x2 + y2 = 4
⇒ (x + y)2 - 2xy = 4
⇒ 22 - 2xy = 4
⇒ 2xy = 4-4
∴ xy = 0
⇒ (x + y)2 - 2xy = 4
⇒ 22 - 2xy = 4
⇒ 2xy = 4-4
∴ xy = 0
∴ x3 + y3 = (x + y)3 - 3xy (x + y)
= (2)3 - 3 × 0 × 2
= 8
= (2)3 - 3 × 0 × 2
= 8
