Question

(1,2),(2,3) and (-1,x) are collinear find x​

Answer 1

Answer:

Let the points A(1,2),B(1,x) and C(2,3) are collinear then area of triangle made by these points will be zero.

⇒

2

1

[x

1

(y

2

−y

3

)+x

2

(y

3

−y

1

)+x

3

(y

1

−y

2

)]

⇒

2

1

[(x−3)+(−1)(3−2)+2(2−x)]=0

⇒x−3−1+2(2−x)=0

⇒x−3−1+4−2x=0

⇒−x−4+4=0

⇒x=0