Tính chất của dãy tỉ số bằng nhau

Home Toán lớp 7 - Sách KNTT Bài 21: Tính chất của dãy tỉ số bằng nhauBài tập trung bình

{"common":{"save":0,"post_id":"5792","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8142","post_id":"5792","mon_id":"1158532","chapter_id":"1158659","question":"Tìm hai s\u1ed1 x và y, bi\u1ebft: $\\dfrac{x}{4}=\\dfrac{y}{5}$<\/span> và x + y = 27<\/p>","options":["A. <\/strong>x = 15; y = 12","B. <\/strong>x = –12; y = –15","C. <\/strong>x = 12; y = 12","D. <\/strong>x = 12; y = 15"],"correct":"4","level":"2","hint":"Áp d\u1ee5ng tính ch\u1ea5t c\u1ee7a dãy t\u1ec9 s\u1ed1 b\u1eb1ng nhau: $\\dfrac{a}{b}=\\dfrac{c}{d}=\\dfrac{a+c}{b+d}=\\dfrac{a-c}{b-d}$<\/span><\/p>","answer":"Theo tính ch\u1ea5t c\u1ee7a dãy t\u1ec9 s\u1ed1 b\u1eb1ng nhau, ta có:<\/p>$\\dfrac{x}{4}=\\dfrac{y}{5}=\\dfrac{x+y}{4+5}=\\dfrac{27}{9}=3$<\/span><\/p>Suy ra x = 3 . 4 = 12 và y = 3 . 5 = 15<\/p>V\u1eady \u0111áp án \u0111úng là D.  <\/strong>x = 12; y = 15<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"1","date":"2022-05-27 02:19:05","option_type":"txt","len":2},{"id":"8144","post_id":"5792","mon_id":"1158532","chapter_id":"1158659","question":"Tìm hai s\u1ed1 a, b bi\u1ebft: $\\dfrac{a}{3}= \\dfrac{b}{4}$<\/span> và $a - b=1,5$<\/span><\/p>","options":["A. <\/strong>$a=4,5;\\space b=6$<\/span>","B. <\/strong>$a=-4,5;\\space b=-6$<\/span>","C. <\/strong>$a=-4,5;\\space b=6$<\/span>","D. <\/strong>$a=-6;\\space b=-4,5$<\/span>"],"correct":"2","level":"2","hint":"Áp d\u1ee5ng tính ch\u1ea5t c\u1ee7a dãy t\u1ec9 s\u1ed1 b\u1eb1ng nhau: $\\dfrac{a}{b}=\\dfrac{c}{d}=\\dfrac{a+c}{b+d}=\\dfrac{a-c}{b-d}$<\/span><\/p>","answer":"Áp d\u1ee5ng tính ch\u1ea5t c\u1ee7a dãy t\u1ec9 s\u1ed1 b\u1eb1ng nhau, ta có:<\/p>$\\dfrac{a}{3}= \\dfrac{b}{4}=\\dfrac{a-b}{3-4}=\\dfrac{1,5}{-1}=-1,5$<\/span><\/p>Suy ra  <\/strong>$a=(-1,5).3=4,5$<\/span>  và  $b=(-1,5).4=-6$<\/span><\/p>\u0110áp án \u0111úng là B. <\/strong>$a=-4,5;\\space b=-6$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"1","date":"2022-05-27 02:26:03","option_type":"math","len":0},{"id":"8146","post_id":"5792","mon_id":"1158532","chapter_id":"1158659","question":"Tìm hai s\u1ed1 x và y, bi\u1ebft: $\\dfrac{x}{-2}=\\dfrac{y}{5}$<\/span> và x + y = 6<\/p>","options":["A. <\/strong>x = –4; y = 10","B. <\/strong>x = 10; y = –4","C. <\/strong>x = 4; y = –10","D. <\/strong>x = 4; y = 10"],"correct":"1","level":"2","hint":"Áp d\u1ee5ng tính ch\u1ea5t c\u1ee7a dãy t\u1ec9 s\u1ed1 b\u1eb1ng nhau: $\\dfrac{a}{b}=\\dfrac{c}{d}=\\dfrac{a+c}{b+d}=\\dfrac{a-c}{b-d}$<\/span><\/p>","answer":"Áp d\u1ee5ng tính ch\u1ea5t c\u1ee7a dãy t\u1ec9 s\u1ed1 b\u1eb1ng nhau, ta có: <\/p>$\\dfrac{x}{-2}=\\dfrac{y}{5}=\\dfrac{x+y}{-2+5}=\\dfrac{6}{3}=2$<\/span><\/p>Suy ra x = 2 . (–2) = –4 và y = 2 . 5 = 10<\/p>V\u1eady \u0111áp án \u0111úng là  A. <\/strong>x = –4; y = 10<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"1","date":"2022-05-27 02:33:49","option_type":"txt","len":2}]}