We call ‘p’ a good number if the inequality x 2 + x + 1 2 x 2 + 2 x + 3 is smaller than or equal to p for any integral x. Find the smallest integral good number
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My approach was same but some people...in my friend circle and on brilliant say that answer is 4
For x=-0.5 the fraction takes value 10/3 which is larger than 3, but since we were asked for integral (integer) and 4 is not correct its got to be 3. NOT the best problem tho..
[ x 2 + x + 1 ] 2 [ x 2 + x + 1 ] + 1 , Let the polynomial be X
X 2 X + 1 = 2 + X 1
2 + X 1 ≤ p
Lowest possible answer to this inequality is 2 when X approach ∞
Since we need integral value that is defined, taking limits is not an option because 2 is never reached and since the polynomial doesn't take negative values the only possible answer here is 3.
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Knowing that x 2 + x + 1 2 x 2 + 2 x + 3 = 2 + x 2 + x + 1 1 , we require (x^2 + x + 1)|1 for x ∈ R . Hence:
x 2 + x + 1 = ± 1 .
If it's equal to 1, then x 2 + x = 0 ⇒ x = 0 , − 1 . If it's equal to -1, then x 2 + x + 2 = 0 ⇒ x = 2 − 1 ± 7 i and we do not have real roots! Therefore the least integral value of p such that 2 + x 2 + x + 1 1 ≤ p holds is 3 .