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Values of 'a' for which x^{2}-ax+a\geqslant 0  \forall   x\; \epsilon \; R  are

  • Option 1)

    a\: \epsilon R

  • Option 2)

    a\: \epsilon \: \left ( 0,5 \right )

  • Option 3)

    a\: \epsilon \: R^{+} 

  • Option 4)

    a\: \epsilon \: \left[0,4 \right ]

 

Answers (1)

coeff of x^{2}=1> 0 , so only other required condition is D\leqslant 0

\Rightarrow \: a^{2}-4a\leqslant 0

\Rightarrow \: a\, \epsilon \, \left [ 0,4 \right ]

\therefore Option (D)

 

Quadratic Expression ax^2 + bx + c is non negative -

ax^{2}+bx+c\geqslant 0 for all x \epsilon R  When  a> 0  &   b^{2}-4ac\leq 0    \left ( \; a,b,c\; \epsilon\; R \right )

 

 

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Option 1)

a\: \epsilon R

This is incorrect

Option 2)

a\: \epsilon \: \left ( 0,5 \right )

This is incorrect

Option 3)

a\: \epsilon \: R^{+} 

This is incorrect

Option 4)

a\: \epsilon \: \left[0,4 \right ]

This is correct

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Vakul

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