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\(\text{ The function }f\left(x\right)=\frac{{x}^{2}+2x-15}{{x}^{2}-4x+9},x\in R\text{ is }\) [JEE Main 2024, 6 Apr (Shi…

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\(\text{ The function }f\left(x\right)=\frac{{x}^{2}+2x-15}{{x}^{2}-4x+9},x\in R\text{ is }\)

[JEE Main 2024, 6 Apr (Shift 1)]

a

both one-one and onto.

b

neither one-one nor onto.

c

onto but not one-one.

d

one-one but not onto.

✓ Correct answer: b)

neither one-one nor onto.

Explanation

\(\begin{aligned}&f(x)=\frac{x^2+2x-15}{x^2-4x+9}\\&f'(x)=\frac{\left(x^2-4x+9\right)(2x+2)-\left(x^2+2x-15\right)(2x-4)}{\left(x^2-4x+9\right)^2}\\&f'(x)=\frac{-6x^2+48x-42}{\left(x^2-4x+9\right)^2}\end{aligned}\)

So \(f'(x)\) is \(+\)ve and \(-\)ve, hence \(f(x)\) is many-one and into.

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