1.

The product of two successive natural numbers is 1980. Which is the smaller number ? (a) 34 (b) 35 (c) 44 (d) 45

Answer»

(c) 44

x(x + 1) = 1980

⇒ x2 + x - 1980 = 0

⇒ x2 + 45x - 44x - 1980 = 0

⇒ x(x + 45) - 44(x + 45) = 0

⇒ (x + 45)(x - 44) = 0

⇒ x = - 45, 44 

Rejecting –45 , x = 44.



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