Q3

Algebra Level 3

Number of integral solutions of x + 2 x 2 + 1 > 1 2 \frac { x+2 }{ { x }^{ 2 }+1 } >\frac { 1 }{ 2 } is :

3 1 0 2

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3 solutions

Maninder Dhanauta
Oct 16, 2015

I hope this is a clear solution

We can also use wavy curve method in the inequality to obtain the range..

Sagar Shah - 5 years, 2 months ago

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@sagar shah Exactly what is this wavy curve method?

Maninder Dhanauta - 5 years, 2 months ago

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Refer to this wiki.. https://brilliant.org/wiki/wavy-curve-method/

Sagar Shah - 5 years, 1 month ago
Atul Shivam
Oct 17, 2015

Solving the inequality we will get range of x from (-1,3) so total integers in between this will be 0,1,2 and that's the answer ie. 3 integral solutions

x 2 x 2 + 1 > 1 2 \dfrac{x^2}{x^2+1}>\dfrac{1}{2}

Cross-multiplying(since no real x x can have x 2 + 1 = 0 x^2+1=0 ),

x 2 2 x 3 < 0 x^2-2x-3 <0 ( x 3 ) ( x + 1 ) < 0 (x-3)(x+1)<0 x [ 0 , 2 ] \implies x \in [0,2] We need integer values of x x x { 0 , 1 , 2 } \implies x\in \{0,1,2\} No. of values = 3 \text{No. of values}=\boxed{3}

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