求教一题：QWD 和这两天实际考题很相似

S is a set of points in the plane.  How many distinct triangles can be drawn that have three of the points in S as vertices?

(1)     The number of distinct points in S is 5.

(2)     No three of the points in S are collinear.

Should the answer be (C)?

Any three points, if not collinear and not overlapped, should be able to decide a distinct triangle.

And a triangle requires three verticle points to be non collinear and, obviously, not occupying the same spot.

谢谢，上一题的答案是c,再帮我看看下面这道题

In the decimal representation of x, where 0 < x < 1, is the tenths digit of x nonzero?

(1)     16x is an integer.

(2)     8x is an integer.

Since 8x is an integer and x>0 ---> 8x>=1--->x>=0.125, --> tenths digit of x must be nonzero

16x>=1 --> x>= 0.0625 only

So the answer should be (B)