Find the value of `x` for which the points `(x-1),\ (2,1)a n d\ (4,5)\ ` are collinear.

Explanation

Let the given points be` A(x,-1)`, `B(2,1)` and `C(4,5)`.

Slope of A B=`frac[1+1][2-x]=frac[2][2-x]`


Slope of B C=`frac[5-1][4-2]=frac[4]2=2`


It is given that the points` (x,-1),(2,1)`and` (4,5)` are collinear.

therefore Slope of A B= Slope of B C


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