C-03-Q031mediumsingle_mcqSquare of (3a−7b)=?(3a-7b) = ?(3a−7b)=?a9a2−42ab+49b29a^2 - 42ab + 49b^29a2−42ab+49b2b9a2+42ab+49b29a^2 + 42ab + 49b^29a2+42ab+49b2c9a2−42ab−49b29a^2 - 42ab - 49b^29a2−42ab−49b2d9a2−21ab+49b29a^2 - 21ab + 49b^29a2−21ab+49b2ব্যাখ্যাUsing (p−q)2=p2−2pq+q2(p-q)^2=p^2-2pq+q^2(p−q)2=p2−2pq+q2 with p=3a, q=7bp=3a,\ q=7bp=3a, q=7b gives 9a2−2(3a)(7b)+49b2=9a2−42ab+49b29a^2-2(3a)(7b)+49b^2=9a^2-42ab+49b^29a2−2(3a)(7b)+49b2=9a2−42ab+49b2.