About Lesson
12.2 Linear Equations 直线方程式
1. (a) A straight line has gradient -2 and passes through point (3, -1), find the equation of the line in general form.
一直线其斜率是-2 且经过点 (3, -1), 求该直线的一般式方程式。
(b) Find the x-intercept, y-intercept and gradient of the line 3x– 2y = 18
求直线3x– 2y = 18 的x-截距，y-截距和斜率。
Answer :
(a) 2x + y – 5 = 0
(b) 6, -9, 1.5
2. Given that A(-1, 5) and B(3, -1).
已知A(-1, 5) 和 B(3, -1).
(a) Find the equation of line AB in gradient form,
求直线AB的斜截式方程式。
(b) Find the coordinate of point P if P separate segment AB in ratio 1 : 3,
求点P的坐标若P把AB线段分成1 : 3
(c) If Q is the x-intercept of AB, find
若Q是AB 的 x-截点，求
(i) the ratio AQ : QB,
AQ : QB的比例，
(ii) coordinate Q
Q的坐标
Answer :
(a) y=
(b) (0, 3
)
(c) (i) 5 : 1
(ii) (2
, 0)
3. The line x – y + k ( x + y + 4 ) = 0 will pass through a certain point for any value of k. Find the value of k if the line is
对所有的k值, 直线x – y + k ( x + y + 4 ) = 0必经过一固定点, 求k之值若此直线为
(a) horizontally
水平线
(b) vertically
垂直线
Answer :
(a) –1
(b) 1