Maths

Let the original value of x be k, then original value of y = 3√k

New value of x = k*(1 + 21%) = 1.21k

New value of y = 3 * 11√k = 33√k = 33√x

Percentage change of y :

3√x (1 + 10) = 33√x

10 = 1000%

So,
% change of y = 100%

條題目好怪，有冇禁多啊!!!!!!!!!!

錯了請提醒!!!!!!!


2010-08-20 10:29:06 補充：
打錯!!!

Let the original value of x be k, then original value of y = 3√k

New value of x = k*(1 + 21%) = 1.21k

New value of y = 3 * sqrt1.21k = 3.3√k = 3.3√x

Percentage change of y :

3√x (1 + 0.1) = 3.3√x

0.1 = 10%

So,
% change of y = 10%

2010-08-20 11:24:26 補充：
你快贊助2點

2010-08-20 12:58:00 補充：
Adam, 我建議你刪除你的回答，因為...........

QQ仔仔2010-08-20 10:48:39 補充

唔該你呀!
過多幾個鐘後先揀得最佳^ha^

Suppose y = 3√x .
If x is increased by 21% , what is the percentage change of y ?

Let the original value of x be k , then original value of y = 3√k

New value of x = k * (1 + 21%) = 1.21k

New value of y = 3√(1.21k) = 3*1.1√k = 3.3√k

Percentage change of y = {[(3.3√k) - (3√k)] / 3√k} * 100% = 10%