xdf-ds-180 xdf-ps-211

marian_w

180.If x³y⁴=5000,is y=5?

(1)y is a positive integer

(2)x is an integer

答案是C，我选了A不知道为什么必须要（2）呢？

211.If the number of square units in the area of circle C is twice the number of linear units in the circumference of C,what is the number of square units in the area?

A.4

B.8

C.4π

D.8π

E.16π

答案是E不太理解啊，是不是需要画图?

谢谢大家帮忙！

erikajin

1 如果x是分数，y不能确定

2 不用画图， 圆的面积数值是周长的2倍