Đại lượng tỉ lệ nghịch

Home Toán lớp 7 - Sách KNTT Bài 23: Đại lượng tỉ lệ nghịchBài tập cơ bản

{"common":{"save":0,"post_id":"5797","level":1,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8277","post_id":"5797","mon_id":"1158532","chapter_id":"1158659","question":"N\u1ebfu \u0111\u1ea1i l\u01b0\u1ee3ng y liên h\u1ec7 v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng x theo công th\u1ee9c <input class=\"_tit_hoi\" disabled=\"disabled\" type=\"text\"\/> thì ta nói y t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$<\/span> ($\u200b\u200ba$<\/span> là m\u1ed9t h\u1eb1ng s\u1ed1 khác 0).<\/p>","options":["A. <\/strong>$y=a.x$<\/span>","B. <\/strong>$y=\\dfrac{a}{x}$<\/span>","C. <\/strong>$y=a+x$<\/span>","D. <\/strong>$y=a-x$<\/span>"],"correct":"2","level":"1","hint":"","answer":"N\u1ebfu \u0111\u1ea1i l\u01b0\u1ee3ng y liên h\u1ec7 v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng x theo công th\u1ee9c $y=\\dfrac{a}{x}$<\/span><\/span> thì ta nói y t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $\u200b\u200ba$<\/span> ($\u200b\u200ba$<\/span> là m\u1ed9t h\u1eb1ng s\u1ed1 khác 0).<\/p>\u0110áp án \u0111úng là  B. $y=\\dfrac{a}{x}$<\/span><\/strong><\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"1","date":"2022-05-28 09:09:04","option_type":"math","len":0},{"id":"8288","post_id":"5797","mon_id":"1158532","chapter_id":"1158659","question":"N\u1ebfu y t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$<\/span> ($a\\ne0$<\/span>) thì x t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi y theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 <input class=\"_tit_hoi\" disabled=\"disabled\" type=\"text\"\/> và ta nói x và y là hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch.<\/p>","options":["$a^2$<\/span>","$\\dfrac{a}{2}$<\/span>","$a$<\/span>","$\\dfrac{1}{a}$<\/span>"],"correct":"3","level":"1","hint":"","answer":"N\u1ebfu y t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$<\/span> ($a\\ne0$<\/span>) thì x t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi y theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$<\/span><\/span> và ta nói x và y là hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch.<\/p>\u0110áp án \u0111úng là $a$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"1","date":"2022-05-28 09:34:27","option_type":"math","len":0},{"id":"8293","post_id":"5797","mon_id":"1158532","chapter_id":"1158659","question":"Cho b\u1ea3ng sau:<\/p><table border=\"1\" cellpadding=\"1\" cellspacing=\"1\" style=\"width: 500px;\"><tbody> <tr> <td>x<\/strong><\/td> <td>10<\/td> <td>8<\/td> <td>4<\/td> <td>2<\/td> <\/tr> <tr> <td>y<\/strong><\/td> <td>10<\/td> <td>12,5<\/td> <td>25<\/td> <td>50<\/td> <\/tr><\/tbody><\/table>Khi \u0111ó x và y là hai \u0111\u1ea1i l\u01b0\u1ee3ng <input class=\"_tit_hoi\" disabled=\"disabled\" type=\"text\"\/><\/p>","options":["A. <\/strong>t\u1ec9 l\u1ec7 ngh\u1ecbch","B. <\/strong>t\u1ec9 l\u1ec7 thu\u1eadn","C. <\/strong>b\u1ea5t kì","D. <\/strong>C\u1ea3 A, B, C \u0111\u1ec1u sai"],"correct":"1","level":"1","hint":"N\u1ebfu hai \u0111\u1ea1i l\u01b0\u1ee3ng x và y t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi nhau thì tích hai giá tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a chúng luôn không \u0111\u1ed5i (và b\u1eb1ng h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7)<\/p>t\u1ee9c là $x_1.y_1=x_2.y_2=...=a$<\/span><\/p>","answer":"Xét tích hai giá tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a x và y ta có:<\/p>10 . 10 = 8 . 12,5 = 4 . 25 = 2 . 50 = 100<\/span><\/p>Suy ra x và y là hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch (theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 100)<\/p>V\u1eady \u0111áp án \u0111úng là A. <\/strong>t\u1ec9 l\u1ec7 ngh\u1ecbch<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"1","date":"2022-05-28 09:54:10","option_type":"txt","len":2}]}