if points (1, 2) , ( x, -1 ) and ( 4 , 5 ) are collinear then value of x
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Hey I think this can be ur answer!!
SO option (a) =-2 is correct answer!!
SO option (a) =-2 is correct answer!!
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Let A(1,2) , B(x, -1) , C(4,5)
Now As points A,B and C are collinear
=> SlopeAB = SlopeAC
=> -1 -2 / x - 1 = 5 - 2 / 4 - 1
=> -3 / x - 1 = 3 / 3
=> -3 / x -1 = 1
taking reciprocal on both sides gives,
x - 1 / -3 = 1
=> x - 1 = 1 x ( - 3)
=> x - 1 = - 3
=> x = -3 + 1 = -2
so , x = -2
Now As points A,B and C are collinear
=> SlopeAB = SlopeAC
=> -1 -2 / x - 1 = 5 - 2 / 4 - 1
=> -3 / x - 1 = 3 / 3
=> -3 / x -1 = 1
taking reciprocal on both sides gives,
x - 1 / -3 = 1
=> x - 1 = 1 x ( - 3)
=> x - 1 = - 3
=> x = -3 + 1 = -2
so , x = -2
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