Q128 / 200 · AP EAMCET 2002 · Mathematics

If 3 is a root of $x^2+k x-24=0$. It is also a root of

  • A
    $x^2+5 x+k=0$
  • B
    $x^2+k x+24=0$
  • Correct answer
    C
    $x^2-k x+6=0$
  • D
    $x^2-5 x+k=0$

Solution

We have, 3 is the roots of $x^2+k x-24=0$ Then, $9+3 k-24=0$ $$ 3 k=15 \Rightarrow k=5 $$ Also, $x^2-k x+6=0$ $$ 9-3 x+6=0 \Rightarrow k=5 $$ Thus 3 is also the root of $x^2-k x+6=0$

Hence, the correct answer is option: 'C'.

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