PP1 PS 142

[lovelymaomo[origen]]

142.
The rate of a certain chemical reaction is directly proportional to the square of the concentratin of chemical A present
and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by
100 present,which of the following is clostest to the percent change in the conceratration 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

這題PP詳解有
但我看不懂題目在說什麼?
所以也看不懂詳解= =
想要請問大家了,感恩啊~~~

[christinehsu]

化學反應與A^2成正比，並與B成反比。
設化學反應速度為X=A^2*B
若B增加100%，則為兩個B，所以化學反應的速度就會慢兩倍--->則X為1/2X
要維持一定的速度則勢必要增加A。
1=A^2 * 1/2 ---> A^2=2 ----->A=根號2=1.4142......
所以A要增加 41%左右
則答案為D