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AP EAMCET · Maths · Functions

If \(f: R \rightarrow A\) defined by \(f(x)=\frac{1}{x^2+2 x+2}\), \(\forall x \in R\) is surjective, then \(A=\)

  1. A \([1, \infty]\)
  2. B \((1, \infty)\)
  3. C \([0,1]\)
  4. D \((0,1]\)
Verified Solution

Answer & Solution

Correct Answer

(D) \((0,1]\)

Step-by-step Solution

Detailed explanation

Since, the quadratic expression \[ \begin{aligned} & x^2+2 x+2=(x+1)^2+1 \in[1, \infty), \forall x \in R \\ \Rightarrow \quad & \frac{1}{(x+1)^2+1} \in(0,1] \end{aligned} \] For \(f(x)=\frac{1}{x^2+2 x+2}, \forall x \in R\) is surjective, then set \[ A=(0,1] \]