Q33 of 66 Page 7

A point P divides the line segment joining the points A (3, -5) and B (-4, 8) such that . If P lies on the line x + y = 0, then find the value of K.(CBSE 2012)

We have


Given that,


For coordinates of P, we have (x1, x2)=(3,-4) and (y1,y2)=(-5,8)


Also, by the section formula, we have



So, substituting the corresponding values in the section formula, we get the coordinate of P as .


And it’s given that P lies on line x + y = 0, this implies that P coordinate which represented as (x,y) can be substituted in the line to find the value of K.


x + y = 0


⇒


⇒


⇒


⇒ 4K – 2 = 0


⇒ 4K = 2


⇒ K = 2/4 = 1/2


Thus, the value of k = 1/2

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