Question 564773
can you explain two point formula please,thank you. 
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The point-slope formula is:
y-y1 = m(x-x1)
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But m = (y2-y1)/(x2-x1)
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So y-y1 = [(y2-y1)/(x2-x1)](x-x1)
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That is the 2-point formula for a line
with points at (x1,y1) and (x2,y2).
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Cheers,
Stan H.