請教一題數....

liangg

1.Let x and y be two variables such that xy" is a constaant . When x is doubled, what is    the  % change of y??  (" = 2 次方)

sapphire

xy^2 = k    where k is a constant

When x is doubled,
2x (y / √2)^2 = k

So y becomes (1 / √2) y,
% change = 70.7 %

liangg

我明la!! 好多謝你的解答!!!