麻烦大家帮我看一道data题。多谢了。

candybobo711

in the xy-plane, if line k has negative slope and passes through the point (-5, r), is the x-intercept of line k positive？1. the slope of line k is -5
2. r>0

sdcar2010

楼上的NN，is the x-intercept of line k positive，应该是和X轴的交点吧

-- by 会员 MelissaW (2011/1/5 21:21:43)

Very true.

If the line k pass through point (0, b) and (-5, r), then (b-r)/(0-(-5))=k.

So b = 5k+r
The x-axis intercept a = (-b)/k = -5 -r/k

1) insufficient.  r =1000 or -10000.
2) insufficient. r =1000, k=5.  r= 1000, k=-5.

1) and 2).  Insufficient. r=5, k=-5, a= -4.  r= 100, k=-5, a = 15

MelissaW

楼上的NN，is the x-intercept of line k positive，应该是和X轴的交点吧

sdcar2010

If the line k pass through point (0, b) and (-5, r), then (b-r)/(0-(-5))=k.

So b = 5k+r

1) insufficient.  r =1000 or -10000.
2) insufficient. r =1, k=-5.  r= 1000, k=-5.

1) and 2).  Insufficient. Same as 2).