Answers

2014-06-23T13:59:35+05:30
M=y2-y1/x2-x1 (4,2) (7,5) (9,7) M1=5-2/7-4=1 M2=7-5/9-7=1 M3=7 -2/9-4 =1 M1= m2= m3= 1 all the three points have same slope That is they lie in the same line
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2014-06-23T14:03:06+05:30
Points are (4,2) ,(7,5) & (9,7)
equation of line joining the points (4,2) & (7,5) is
y - 2 = (5-2)/(7-4) (x-4)
y - 2 = x - 4
x - y - 2 = 0
if the point (9,7) lie on the line then it satisfy the equation
9 - 7 - 2 = 0
0 = 0
hence points (4,2),(7,5) & (9,7) lie on a straight line
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