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<span class='text_page_counter'>(1)</span>Trêng THCS Minh NghÜa Hä vµ Tªn:.................................. Líp :6..... §Ò :A. Bµi kiÓm tra sè 2 (tiÕt 39) Ngµy kiÓm tra :......./............/.2012. §iÓm. §Ò bµi. M«n : sè häc líp 6 Thêi gian : 45 phót. Lêi phª cña thÇy c« gi¸o. I. PHẦN TRẮC NGHIỆM: (2điểm) - Hãy khoanh tròn vào chữ cái câu em lựa chọn là đúng nhất ?. Câu 1: (1 ®iÓm) A. Nếu mỗi số hạng không chia hết cho 5 thì tổng không chia hết cho 5. B. Nếu tổng chia hết cho 5 thì mỗi số hạng chia hết cho 5. C. Nếu mỗi số hạng chia hết cho 5 thì tổng chia hết cho 5. D. Không có câu nào đúng. Câu 2: (1 ®iÓm) Hai hay nhiều số nguyên tố cùng nhau khi: A. Các số đó đều là số lẻ B. ƯCLN của các số đã cho bằng 1 C. ƯCLN của các số đó lớn hơn 1 D. Hai câu B và C đều đúng II. PHẦN TỰ LUẬN: (8 điểm) Câu 1: (4điểm) Tìm ƯCLN, BCNN rồi tìm tập hợp các ƯC, BC của các số a, b, c, biết: a = 30 ; b = 36 ; c = 12. Câu 2: (1,5điểm) Tìm số tự nhiên x biết: x  5; x  6 ; x  10 và 0 < x < 140. Câu 3: Toán giải (2,5 điểm) Lớp 6A có khoảng từ 20 đến 50 học sinh, biết rằng khi xếp hàng 3, hàng 6, hàng 9 đều vừa đủ. Tìm số học sinh của lớp 6A? Bµi Lµm ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ...................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ........................................................................................................................................................................................

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<span class='text_page_counter'>(3)</span> ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ....................................................................................................................................................................................... ........................................................................................................................................................................................ ĐÁP ÁN ĐỀ A I. PHẦN TRẮC NGHIỆM: (3 điểm) (Mỗi câu đúng 1 điểm) Câu. 1. 2. 3. Đáp án. C. B. A. II. PHẦN TỰ LUẬN: (7điểm) Câu 1: (2,5điểm) 30 = 2 . 3 . 5 ;36 = 22 . 32 ;42 = 2 . 3 . 7 (0,5đ) ƯCLN(30; 36; 42) = 2 . 3 = 6. (0,5đ). ƯC(30; 36; 42) = {1; 2; 3; 6}. (0,5đ). BCNN(30; 36; 42) = 22 . 33 . 5 . 7 = 1260. (0,5đ). BC(30; 36; 42) = {0; 1260; 2520; ...}. (0,5đ). Câu 2: (1,5điểm) Vì: x  5 ; x  6 ; x  10 và 0 < x < 140 Nên: x  BC(5; 6; 10) 5=5 ;. 6=2.3 ;. 10 = 2 . 5. BCNN(5; 6; 10) = {0; 30; 60; 90; 120; 150; ...} Vì: 0 < x < 140 Nên x  {30; 60; 90; 120} Câu 3: (3điểm) Gọi a là số học sinh cần tìm.. Theo đề bài. a  3 ; a  6 ; a  9 và 20 ≤ a ≤ 50.

<span class='text_page_counter'>(4)</span> Nên: a  BC(3; 6; 9) và 20 ≤ a ≤ 50 3 = 3 ;6 = 2 . 3 ;. 9 = 32. BCNN(3; 6; 9) = 2 . 32 = 18 BC(3; 6; 9) = {0; 18; 36; 72; ...} Vì: 20 ≤ a ≤ 50 Nên: a = 36. Vậy số học sinh cần tìm là 36 em..

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