Giải hệ hai phương trình bậc nhất hai ẩn

Home Lớp 9 Toán lớp 9 - Sách Kết nối tri thức Bài 2: Giải hệ hai phương trình bậc nhất hai ẩnBài tập trung bình

{"common":{"save":0,"post_id":"7374","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"6998","post_id":"7374","mon_id":"1159278","chapter_id":"1159281","question":"Gi\u1ea3i h\u1ec7 ph\u01b0\u01a1ng trình b\u1eb1ng ph\u01b0\u01a1ng pháp th\u1ebf.<\/p>Nghi\u1ec7m c\u1ee7a h\u1ec7 ph\u01b0\u01a1ng trình $\\begin{cases}x+2y=5\\\\x-y=-1\\end{cases}$<\/span>  là<\/span><\/p>","options":["A.<\/strong> (1 ; 1)","B.<\/strong> (0 ; –2)","C.<\/strong> (–1 ; 0)","D.<\/strong> (1 ; 2)"],"correct":"4","level":"2","hint":"T\u1eeb ph\u01b0\u01a1ng trình (2) ta có: x = y – 1. Th\u1ebf vào ph\u01b0\u01a1ng trình (1) ta \u0111\u01b0\u1ee3c y – 1 + 2y = 5<\/p>","answer":"Ch\u1ecdn D.<\/strong> (1 ; 2).<\/span><\/p>Ta có: $\\begin{cases}x+2y=5\\text{ (1)}\\\\x-y=-1\\text{ (2)}\\end{cases}$<\/span>.<\/p>T\u1eeb ph\u01b0\u01a1ng trình (2) ta có: x = y – 1. Th\u1ebf vào ph\u01b0\u01a1ng trình (1) ta \u0111\u01b0\u1ee3c y – 1 + 2y = 5 hay 3y = 6 suy ra y = 2. T\u1eeb \u0111ó x = 2 – 1 = 1. V\u1eady h\u1ec7 ph\u01b0\u01a1ng trình \u0111ã cho có nghi\u1ec7m (1 ; 2).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-09-30 02:34:30","option_type":"txt","len":2},{"id":"7000","post_id":"7374","mon_id":"1159278","chapter_id":"1159281","question":"Nghi\u1ec7m c\u1ee7a h\u1ec7 ph\u01b0\u01a1ng trình $\\begin{cases}-2x+y=7\\text{ (1)}\\\\3x+2y=0\\text{ (2)}\\end{cases}$<\/span> là<\/p>","options":["A.<\/strong> (–2 ; 3)","B.<\/strong> (3 ; –1)","C.<\/strong> (1 ; 0)","D.<\/strong> (1 ; 3)"],"correct":"1","level":"2","hint":"Gi\u1ea3i h\u1ec7 ph\u01b0\u01a1ng trình b\u1eb1ng ph\u01b0\u01a1ng pháp th\u1ebf.<\/p>T\u1eeb (1) ta có: y = 2x + 7. Th\u1ebf vào (2) ta \u0111\u01b0\u1ee3c 3x + 2(2x + 7) = 0<\/p>","answer":"Ch\u1ecdn A.<\/strong> (–2 ; 3).<\/span><\/p>T\u1eeb (1) ta có: y = 2x + 7. Th\u1ebf vào (2) ta \u0111\u01b0\u1ee3c 3x + 2(2x + 7) = 0 hay 7x + 14 = 0 suy ra x = –2. T\u1eeb \u0111ó y = 2.(–2) + 7 = 3. V\u1eady h\u1ec7 \u0111ã cho có nghi\u1ec7m (–2 ; 3).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-09-30 02:38:52","option_type":"txt","len":2},{"id":"7003","post_id":"7374","mon_id":"1159278","chapter_id":"1159281","question":"Nghi\u1ec7m c\u1ee7a h\u1ec7 ph\u01b0\u01a1ng trình $\\begin{cases}5x-4y=4\\text{ (1)}\\\\2x+2y=-2\\text{ (2)}\\end{cases}$<\/span> là<\/p>","options":["A.<\/strong> $(-1;1)$<\/span>","B.<\/strong> $(3;3)$<\/span>","C.<\/strong> $(1;0)$<\/span>","D.<\/strong> $(0;-1)$<\/span>"],"correct":"4","level":"2","hint":"T\u1eeb (2) ta có: x  = – y – 1.<\/p>Th\u1ebf vào (1) ta \u0111\u01b0\u1ee3c 5(– y – 1) – 4y = 4<\/p>","answer":"Ch\u1ecdn D.<\/strong> $(0;-1)$<\/span>.<\/span><\/p>T\u1eeb (2) ta có: x  = – y – 1.<\/p>Th\u1ebf vào (1) ta \u0111\u01b0\u1ee3c 5(– y – 1) – 4y = 4 hay –9y = 9 suy ra y = –1.<\/p>T\u1eeb \u0111ó x = – (–1) – 1 = 0. V\u1eady h\u1ec7 \u0111ã cho có nghi\u1ec7m (0 ; –1).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-09-30 02:43:46","option_type":"math","len":0}]}