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Find the coordinates of which the line crosses the x axis?

The points A and B have coordinates (-2, -7) and (3, 8) respectively.

a) Find the coordinates of the point at which the line through AB crosses the x axis

So I found the gradient of the line, 1/3, so the equation is y -8 = 1/3 x -1. Then I subbed 0 into y, and I got -8 = 1/3x -1. But the answer is 3x - y -1 = 0, and the coordinate is (1/3, 0), which I'm a bit confused about?
Original post by 123Master321
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Don't post full solutions.
(edited 7 years ago)
Original post by RDKGames
Don't post full solutions.


ok sorry
You got the wrong gradient. Also show the brackets because y-8=1/3 x -1 doesn't make sense.
Original post by 123Master321
a) gradient: 8−(−7)3−(−2)=3 \frac{8-(-7)}{3-(-2)} = 3 --> you did change in x divided by change in y


Oh thanks.
Reply 5
Ah I see you're using the simultaneous method, I much prefer y=Mx+c with M being the gradient and c being found by subbing in either A or B
(edited 7 years ago)
Reply 6
Or use Y-y1=m(x-X1) with Y1 and X1 being the coordinates of any point that the line passes. (3,8) or (-2,-7) in your case.

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