MCQ
If $f(x) = \left\{ \begin{array}{l}a{x^2} - b,{\rm{ }}0 \le x < 1\\2,\;{\rm{ }}x = 1\\x + 1,{\rm{ 1}} < x \le 2\end{array} \right.$ is continuous at $x = 1$, then the most suitable value of $a, b$ are
  • A
    $a = 2,\;b = 0$
  • B
    $a = 1,\;b = - 1$
  • C
    $a = 4,\;b = 2$
  • D
    All the above

Answer

$\mathop {\lim }\limits_{x \to 1 - } f(x) = a - b,\mathop {\lim }\limits_{x \to 1 + } f(x) = 2 $
$\Rightarrow a - b = 2$
All the given sets of $a, b$ make $f(x)$ continuous at $x=1$.

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