$\"\"$

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The curve is $\"\"$ and $\"\"$ .

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Consider $\"\"$ .

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Apply derivative on each side with respect to $\"\"$ .

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$\"\"$

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$\"\"$ .

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Consider $\"\"$ .

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Apply derivative on each side with respect to $\"\"$ .

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$\"\"$

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$\"\"$ .

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Find $\"\"$ .

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$\"\"$

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Find $\"\"$ .

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$\"\"$

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$\"\"$ .

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$\"\"$

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Consider $\"\"$ .

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Concave upwards $\"\"$

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$\"\"$

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Multiplying by negative sign will reverse the inequality.

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$\"\"$

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$\"\"$

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Secant value is negative in second and third quadrant that is $\"\"$ .

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Hence, the curve is concave upwards in $\"\"$ .

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$\"\"$

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$\"\"$ , $\"\"$ .

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The curve is concave upwards in $\"\"$ .