1,已知通過M(-6,5各N(-3,C)的直線的斜率是-2求C的值
2,已知A和B的坐標分別為(-1,-6)和(3,0)
若P位於直線AB上,且其X坐標為
-7/3,求P的y坐標
數學問題-斜率
2006-11-04 4:37 pm
回答 (2)
2006-11-04 4:44 pm
✔ 最佳答案
兩點 (x1, x2), (y1, y2)的斜率 = (y2 - y1) / (x2 - x1)1. -2 = (C - 5) / (-3 - (-6))
-2 = (C - 5) / (-3 + 6)
-2(3) = C - 5
-6 = C - 5
C = -6 + 5 = -1
2. A, B, P共線, 故 AB的斜率 = BP的斜率
(-6 - 0) / (-1 - 3) = (y - 0) / (-7 / 3 - 3)
-6 / (-4) = y / (-16 / 3)
y = (6 / 4)(-16 / 3)
= -8
P的y坐標 = -8.
2006-11-04 6:12 pm
1. m=(5-C)/(-6+3)
-2=(5-C)/(-3)
6=5-C
C=-1
2. mAB=[0-(-6)]/[3-(-1)]
mAB=3/2
因為A, X, B are collinear
所以 mAB=mBX
Let x = (-7/3 , y)
mBX=(0-y)/[3-(-7/3)]
1.5=-y/(16/3)
-y=8
y=-8
2006-11-04 10:13:40 補充：
SORRY打錯字當個X係P
-2=(5-C)/(-3)
6=5-C
C=-1
2. mAB=[0-(-6)]/[3-(-1)]
mAB=3/2
因為A, X, B are collinear
所以 mAB=mBX
Let x = (-7/3 , y)
mBX=(0-y)/[3-(-7/3)]
1.5=-y/(16/3)
-y=8
y=-8
2006-11-04 10:13:40 補充：
SORRY打錯字當個X係P
收錄日期: 2021-04-12 22:32:40
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