亚洲男人天堂av,国产一区二区久久精品,国产精品一区二区久久精品,国产精品久久久久久一区二区三区,五月婷婷在线观看视频,亚洲狠狠色丁香婷婷综合

歡迎您訪問每日一練:某商品原價289元,經連續兩次降價后售價為256元!

每日一練:某商品原價289元,經連續兩次降價后售價為256元

更新時間:2024-01-12 12:51:48作者:貝語網校

某商品原價289元,經連續兩次降價后售價為256元,設平均每降價的百分率為x,則下面所列方程正確的是

A.289(1-x)2=256

B.256(1-x)2=289

C.289(1-2x)2=256

D.256(1-2x)2=289

試題答案

A

試題解析

增長率問題,一般用增長后的量=增長前的量×(1+增長率),本題可參照增長率問題進行計算,如果設平均每次降價的百分率為x,可以用x表示兩次降價后的售價,然后根據已知條件列出方程.

解答:根據題意可得兩次降價后售價為289(1-x)2

∴方程為289(1-x)2=256.

故選答A.

點評:本題考查一元二次方程的應用,解決此類兩次變化問題,可利用公式a(1+x)2=c,其中a是變化前的原始量,c是兩次變化后的量,x表示平均每次的增長率.

本題的主要錯誤是有部分學生沒有仔細審題,把答題案錯看成B.

主站蜘蛛池模板: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |