Q12 of 49 Page 167

Find the value of y for which the distance between the points P(2, -3) and Q(10, y) is 10 units.

3 or -9

Let P(2,-3) and Q(10,y)


be the point


⇒ PQ =


⇒ PQ = 10


PQ2 = 102


⇒ (y + 3)2 + 82 = 102


y2 + 6y + 9 + 64 = 100


y2 + 6y-27 = 0


⇒ (y + 9)(y-3) = 0


⇒ y = 9 or y = -3


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