1.

If y is a positive integer such that the distance between the points (–6, –1) and (–6, y) is 12 units, then y = (a) 5 (b) 8 (c) 11 (d) 1

Answer»

(c) 11

Given, \(\sqrt{(-6+6)^2+(y+1)^2}\) = 12

⇒ \(\sqrt{y^2+2y+1}\) = 12

⇒ y2 + 2y + 1 = 144 ⇒ y2 + 2y – 143 = 0 

⇒ y2 + 13y – 11y – 143 = 0 

⇒ y (y + 13) – 11 (y + 13) = 0 

⇒ (y – 11) (y + 13) = 0 ⇒ y = 11 or –13 

The required positive integer is 11.



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