GWD15-23

lansha8uo

 

Q23:

If x ≥ 0 and x = , then, in terms of y, x =

 

A.     – 4y

B.    

C.     y

D.     4y

E.      4y²

Answer:

lansha8uo

If x>or = 0 and x=(8xy-16y^2)^ (1/2)

Ans: 4y

Please explan it.

Thanks!

violetsapphire

这题太简单，等式两边同时平方，得出：

x^2=8xy-16y^2

x^-8xy-16y^2=0

(x-4y)^2=0

x=4y

lansha8uo

Thanks!

I got it now