equation of line

2007-11-30 7:43 pm

1)A triangle has the vertices A(7,1) B(-3,2) and C(4,-4).M is the mid-pint of BC. Find the equation of the medain AM.

2a)Find the equation of a line that passes through the origin and has a slope of -2/3.
2b)Find the value of b for the pointX(5,b)on this line.

3a)Convert the equation of the line7x+2y=14 into the intercept form.[Hint:14divide both sides of the equation]
3b)What are the x-intercept and the y-intercept?

回答 (1)

[匿名]

2007-11-30 10:51 pm

✔ 最佳答案

I try to give some hints and you continue with it on your own.

(1) Step 1: find out coordinates of M (mid-point of BC): x=(7-3)/2, y=......
Step 2: Now you have 2 points, M and A. In a straight line, slope of any 2 points are
constant, thus generally for a line passing through 2 points (X1, Y1) and
(X2, Y2)

(y-Y1)/(x-X1) = (Y2-Y2)/(X2-X1)

substituting coordinates of A & M into the equation, rearranging and
simplying, you can get the equation.
(2)(a) Form of equation tailour made for know slope and y-intercept
y = mx + c
where m= slope of the line
c = y-intercept.
It's given slope = -(2/3), y-intercept = 0 (y=0 when x=0)
............. (now your turn to work it out)
(2)(b) using the equation of 2(a), putting x=5, y=b then you can work out the value b.

3(a) & (b), so far, can you continue?

Cheers, have a nice weekend.

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