Question

18. Find the value of y for which the distance between the points A(3, - 1) and B(11, y) is 10 units.
(C.B.S.E. 2011)​

Answer 1

Answer:

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Answer 2

Answer:

It is given that the distance between the points AB = 10.  

Therefore, AB= √(11-3)2 + (y+1)2  = 10

                      = √82 + (y+1)2 =10

                     = √64+(y+1)2  =10

Squaring on both sides, we get,

 64 +(y+1)2 = 100

64+ y2 + 2y + 1 = 100

y2 + 2y +1 = 100-64=36

y2+2y - 35 = 0

Now, by splitting the middle term method, we get,

y2+ 7y - 5y - 35= 0

y(y+7) -5(y+7)

(y-5) ( y+7)

y = 5 or y = -7

Therefore, the value of 'y' can be either 5 or -7.