gwd math 15-23

jessicafairy

请问这题怎解？先谢了。

Q23:

If x ≥ 0 and x = square root of (8xy-16y^2₎, then, in terms of y, x =

 

 

A.     – 4y

B.   y/4

C.     y

D.     4y

E.      4y²

tomatohuas

x = square root of (8xy-16y^2₎,

所以  x^2=8xy-16y²

 0=x^2-8xy+16y²

^{（x－4y）^2=0}

^x=4y

shiningpenny

楼上解答完全正确