Equation of line

2007-11-30 7:36 pm

1)A line segment passes through a point(8,2) and has a slope of -1/2. What is the equation of this line expressed in the general from?

2)A line cuts the x-axis at(3,0) and cuts the y-axis at(0,7).
(a) Find the equation of this straight line and express in the intercept form.
(b)Express the equation of the line in the slope-interecpt Form.

7)Find the equation of the line which passes through the mid-point of the line joining (7,10) and (5,-4) which slope of -2.

=_=我諗極都唔明

回答 (1)

[匿名]

2007-11-30 10:24 pm

✔ 最佳答案

1) y=ax+b
slope = -1/2 thus

y=-(1/2)x +b

when x=8, y=2 thus
2 = -(1/2)(8)+b
b = 6

The equation: y=-(1/2)x + 6 OR 2y+x-12 = 0

2)(a) let y = mx + c
y intercept = 7 thus

y = mx +7

when x=3, y=0, thus
0 = m(3) + 7
m=-(7/3)

The equation : y = -(7/3)x + 7

2)(b) .... I think you can continue with it yourself. Have some practice.

7) coordinates of the mid-point:
x = (7+5)/2 = 6
y= (10-4)/2 = 3
Thus coordinates of the mid-point: (6,3)
Solpe = -2 (given)

Now that you have a point and a slope, please practice by your own. It's similar to question (1) above.

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