If $x=1$ and $x=2$ are extreme points of $f(x)=\alpha \log x+\beta x^2+x$,where $\alpha$ and $\beta$ are constants,then the value of $\alpha^2+2 \beta$ is

  • A
    $1/9$
  • B
    $3$
  • C
    $3/2$
  • D
    $5$

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