If has two distinct and real roots lying in the interval where , and are positive integers, then find the minimum value of .
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Note that the roots are in ( 0 , 1 ) , and are distinct. Hence, the conditions that we get from the equation are: a + c > b , a > c , b 2 > 4 a c Note that c should be the minimum, since otherwise, c > b and that would imply b 2 > 4 b a ⟹ b > 4 a which is a contradiction in the light of the first two conditions. Also, note that b cannot be equal to c in the light of second and third conditions. Thus the possible ordering of the integers a , b , c are a ≥ b > c or b ≥ a > c . In any case the product a b c will be minimized if we take the ordering a = b > c . In that case to make c as small as possible, take c , and take b = a = 5 , which is the smallest positive integer to satisfy the third condition. Thus the smallest value of the product is 2 5 .