x + y = √7 এবং x - y = √5 হলে, 8xy(x2 + y2) = ?

প্রশ্ন: x + y = √7 এবং x - y = √5 হলে, 8xy(x2 + y2) = ?সমাধান: 8xy(x² + y²)= 4xy × 2(x² + y²)= {(x + y)2 - (x - y)2}{(x + y)2 + (x - y)2}= {(√7)2 - (√5)2}{(√7)2 + (√5)2}= (7 - 5)(7 + 5)= 2 × 12= 24