x + y = 7, x2- y2= 21, x2+ y2= 29 এবং xy = 10 হলে x3- y3= ?

সমাধান:<br />দেয়া আছে, <br />x+y = 7, <br /><br />x²+y² = 29,<br /><br />xy = 10,<br /><br />x²-y² = 21<br />বা, (x+y)(x-y) = 21<br />বা, 7(x-y) = 21<br />বা, (x-y) = 3<br /><br />আমরা জানি, <br />x³-y³ = (x-y) (x²+xy+y²)<br />= = (x-y) (x²+y²+xy)<br />= 3(29+10)<br />= 117<br /><br />উত্তর: 117