[問題]新pp中的題目一問

[ginalee6]

可以幫我解釋一下題目,再教教我怎麼算嗎?我完全有看沒有懂ㄟ~~謝謝!

The rate of a certain chemical reaction is directly proportional to the square of the concentrtion of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100%, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?

a. 100% decrease
b. 50% decrease
c. 40% decrease
d. 40% increase
e. 50% increase


Ans)d

[td91]

試著解看看好了.... 題目說這個化學反應跟 A 的平方成正比，跟 B 成反比，如果B 增加100%，则A 要變化多少才會使整個化學反應式保持不變

因為跟B 反比，所以要chemical reaction 減少100%，也就是除以2
chemical reaction 爲了不變所以要乘 2 回來→ A 就要增加根號2
根號2=1.414
所以1.414-1/1 再乘上百分比close to 40% 囉...所以選 D

參考一下吧，有錯請指正....

[ginalee6]

程度果然有差,我看到題目就傻了...又看幾遍還是想不出來...你真行呀!!
但我覺得是不是應該先乘再除才對?歡迎討論