Q1. The curve C: y=x^2 and the straight line L : y=mx-2m intersect at two points A and B.
(a) Find the range of values of m.
(b)(i) Show that the coordinates of the mid-point of AB are (m/2,(m^2- 4m)/2).
(ii) It is given that the straight line x+y=5 bisects the line segment AB.Using (b)(i), or otherwise, find the value(s) of m.
Q2. It is given that the four points A(0,-2),B(1,-3),C(2,0) and D(k,k) form a quadrilated ABCD. Find the area of this quadrilated.
A maths X2
2009-04-26 6:32 am
回答 (2)
2009-04-26 10:31 am
✔ 最佳答案
as follows:圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/01-8.gif
圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/02-6.gif
2009-04-26 7:37 am
Q1(a)
y=x^2------------(1)
y=mx-2m--------(2)
Sub (2) into (1),
x^2=mx-2m
x^2-mx+2m=0
Because L intersect at two points A and B
so discriminant >0
(-m)2-4(1)(2m)>0
m^2-8m>0
m(m-8)>0
m<0 or m>8
y=x^2------------(1)
y=mx-2m--------(2)
Sub (2) into (1),
x^2=mx-2m
x^2-mx+2m=0
Because L intersect at two points A and B
so discriminant >0
(-m)2-4(1)(2m)>0
m^2-8m>0
m(m-8)>0
m<0 or m>8
參考: myself
收錄日期: 2021-04-22 00:37:37
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090425000051KK02302